Flex shaft—tool connection for power operated rotary knife

ABSTRACT

A flexible shaft drive transmission coupled between a drive motor and a gear train of a power operated tool. The flexible shaft drive transmission includes: an outer casing having a bushing positioned at a tool end of the casing, the bushing defining a longitudinal central opening; lubricant disposed within the outer casing; and an elongated drive transmitting shaft assembly rotatable within the outer casing including a flexible drive transmitting and a coupler fitting affixed to the tool end of the drive transmitting shaft, the coupler fitting including a cylindrical body and an enlarged head extending distally from the cylindrical body, the cylindrical body fitting within the longitudinal central opening of the bushing and the enlarged head having a diameter greater than a diameter of the longitudinal central opening of the bushing. The enlarged head defining a square drive aligned with a central longitudinal axis of the drive transmitting shaft assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a divisional of currentlypending U.S. application Ser. No. 13/434,403, filed on Mar. 29, 2012,published as U.S. Publication No. US-2013-0174424-A1 on Jul. 11, 2013,issuing as U.S. Pat. No. 9,265,263 on Feb. 23, 2016, which is acontinuation-in-part of U.S. application Ser. No. 13/344,760, filed onJan. 6, 2012, published as U.S. Publication No. US-2013-0178296-A1 onJul. 11, 2013, issued as U.S. Pat. No. 8,968,107 on Mar. 3, 2015 All ofthe above-identified U.S. patent applications, published patentapplications, and patents, from which priority is claimed, including,U.S. application Ser. No. 13/434,403 and U.S. Publication No.US-2013-0174424-A1 and U.S. application Ser. No. 13/344,760 and U.S.Publication No. US-2013-0178296-A1, are incorporated herein in theirrespective entireties by reference for any and all purposes.

TECHNICAL FIELD

The present disclosure relates to a drive interface or drive connectionstructure for a flexible shaft drive transmission and a gear train of apower operated tool, such as a power operated rotary knife, to providerotational power from an external drive motor to the gear train of thepower operated tool, and, more specifically, to a drive connectionstructure wherein the flexible shaft drive transmission comprises anouter casing assembly and an elongated drive transmitting shaft assemblyrotatable within the outer casing assembly including a coupler fittingthat is secured to a tool end of the drive transmitting shaft, thecoupler fitting including a cylindrical outer surface to seal against abushing of the outer casing assembly to mitigate leakage of lubricantand an enlarged distal head to maintain an axial position of the drivetransmitting shaft with respect to the outer casing assembly, the driveconnection structure further including a driver assembly releasablysecured between a distal end of the outer casing and a handle assemblyof the power operated tool, the driver assembly including a main tubeand a driver shaft supported for rotation within the main tube by spacedapart bushings positioned at opposite axial ends of the main tube, thedriver shaft operatively coupled between the coupler fitting and thedrive train of the power operated tool.

BACKGROUND

Power operated rotary knives are widely used in meat processingfacilities for meat cutting and trimming operations. Power operatedrotary knives also have application in a variety of other industrieswhere cutting and/or trimming operations need to be performed quicklyand with less effort than would be the case if traditional manualcutting or trimming tools were used, e.g., long knives, scissors,nippers, etc. By way of example, power operated rotary knives may beeffectively utilized for such diverse tasks as taxidermy; cutting andtrimming of elastomeric or urethane foam for a variety of applicationsincluding vehicle seats; and tissue removal or debriding in connectionwith medical/surgical procedures and/or tissue recovery from a body of ahuman or animal donor.

Power operated rotary knives typically include a handle assembly and ahead assembly. The head assembly includes an annular blade housing andan annular rotary knife blade supported for rotation by the bladehousing. The head assembly of a power operated rotary knife alsoincludes a gearbox housing which supports a gear train for rotatablydriving the rotary knife blade. In some instances, the gear trainsupported in the gearbox housing may comprise a single gear, in otherinstances; the gear train may include a plurality of gears for drivingthe rotary knife blade. The gear train is part of a drive assembly forthe power operated rotary knife, the gear train being internal to therotary knife. Power operated rotary knives having various gear trainembodiments including a gear train comprising a single gear and a geartrain including a plurality of gears are disclosed in U.S. patentapplication Ser. No. 13/189,925 to Whited et al., filed on Jul. 25, 2011(“the '925 application”). The '925 application is assigned to theassignee of the present application and is incorporated herein, in itsentirety, by reference.

The drive assembly also includes components external to the poweroperated rotary knife including an external drive motor and a flexibleshaft drive transmission. Motive or rotational power which drives thegear train of the power operated rotary knife is typically provided froman external drive motor and transmitted through a flexible shaft drivetransmission. The flexible shaft drive transmission typically includesan elongated drive transmitting shaft which rotates within an outercasing. The elongated drive transmitting shaft includes a driven fittingat one end of the drive transmitting shaft that engages and is rotatedby the mating drive fitting of the drive motor and a drive fitting atthe opposite end of the drive transmitting shaft that engages androtates a mating driven fitting of the gear train of the power operatedrotary knife. Rotation of the drive transmitting shaft by the externalmotor rotates the gear train of the power operated rotary knife, which,in turn, rotates the rotary knife blade.

The outer casing of a typical flexible shaft drive transmission includesa first, motor end coupling at one end of the outer casing which isadapted to be releasably coupled to a mating coupling of the drivemotor, such that, when the motor end coupling and the drive motorcoupling are engaged, the driven fitting of the drive transmitting shaftengages and is rotationally driven by the drive fitting of the drivemotor. A second, handle assembly coupling at the opposite end of theouter casing is adapted to be releasably coupled to the handle assemblyof the power operated rotary knife such that the drive fitting of thedrive transmitting shaft engages and drives the driven fitting of thegear train of the power operated rotary knife.

Typically, lubricant, such as lubricant grease, is disposed between theouter casing and the drive transmitting shaft of the flexible shaftdrive transmission. One recurring problem with respect to the handleassembly coupling end of the flexible shaft drive transmission is thatlubricant would tend to leak out between the shaft and the outer casing.The drive motor is typically mounted on a hanger positioned above thework area where a power operated rotary knife is manipulated by anoperator to trim or cut a product. Thus, motor end coupling of theflexible shaft drive transmission is typically at a higher verticalposition than the handle assembly coupling end of the flexible shaftdrive transmission. Because of the lower vertical position of the handleassembly coupling, gravity causes the lubricant to migrate or draintoward the handle assembly coupling. Thus, leakage of lubricant betweenthe drive transmitting shaft and the outer casing at the handle assemblycoupling end of the flexible shalt drive transmission typically is amuch greater problem than at the motor coupling end. Various attemptshave been made to minimize lubricant leakage through the handle assemblycoupling end of the shaft drive transmission such as, for example, thestructures disclosed in U.S. Pat. No. 6,3514,949 to Baris et al. andU.S. Pat. No. 7,153,202 to Rosu et al., both of which are assigned tothe assignee of the present disclosure. However, the problem persisted.

At least in part because of the loss of lubricant through leakage, inprior flexible shaft drive transmissions, the drive transmitting shaftwould have to be periodically removed from the outer casing to injectnew lubricant into the transmission. If sufficient lubricant leaks outbetween the drive transmitting shaft and the outer casing, undesirablefriction and heat will be generated by contact between the rapidlyrotating drive transmitting shaft and the stationary outer casing.Without the periodic disassembly of the shaft drive transmission toinject new lubricant into the outer casing of prior flexible shaft drivetransmissions, the operating life of the drive transmitting shaft andthe outer casing would be significantly reduced because of increasedheat and wear resulting from lack of sufficient lubricant. However,periodic maintenance of the shaft drive transmission, like any requiredmaintenance, is costly in terms of both labor required for maintenanceand downtime of the equipment.

An additional problem with prior flexible shaft drive transmissionstemmed from the fact that the drive transmitting shaft was not securedwithin the casing. Specifically, when the motor end coupling is releasedfrom the drive motor coupling, the drive transmitting shaft will tend toslide out of the outer casing. This is both inconvenient for theoperator of the power operated rotary knife and can result incontamination of the flexible shaft drive transmission.

SUMMARY

In one aspect, the present disclosure relates to a flexible shaft drivetransmission coupled between a drive motor and a gear train of a poweroperated tool, the flexible shaft drive transmission comprising: a) anelongated drive shaft assembly including a rotatable drive transmittingshaft extending along a longitudinal axis, a first driven fitting at oneend of the drive transmitting shaft and a second drive fitting at asecond end of the drive transmitting shaft, the first driven fitting andthe second drive fitting rotating with the drive transmitting shaft; b)an outer casing including first and second ends and defining athroughbore, the outer casing receiving the drive transmitting shaftwithin the throughbore and supporting the drive transmitting shaft forrotation within the outer casing; and c) a coupling affixed to the firstend of the outer casing and adapted to be releasably connected to thedrive motor, the motor end coupling including a coupling body defining acentral opening through which the drive transmitting shaft passes andhaving an outer surface defining a tapered region, the tapered regionhaving a proximal end and a distal end, the proximal end of the taperedregion of the coupling body being closer in proximity to the outercasing than the distal end of the tapered region, the tapered regiontapering from a first diameter at the proximal end of the tapered regionto a second diameter at the distal end of the tapered region, the firstdiameter being larger than the second diameter.

In another aspect, the present disclosure relates to a flexible shaftdrive transmission coupled between a drive motor and a gear train of apower operated tool, the flexible shaft drive transmission comprising:a) an elongated drive shaft assembly including a rotatable drivetransmitting shaft extending along a longitudinal axis, a first drivenfitting at one end of the drive transmitting shaft and a second drivefitting at a second end of the drive transmitting shaft, the firstdriven fitting and the second drive fitting rotating with the drivetransmitting shaft, the first driven fitting configured to engage adrive fitting of a drive motor; b) an outer casing including first andsecond ends and defining a throughbore, the outer casing receiving thedrive transmitting shaft within the throughbore and supporting the drivetransmitting shaft for rotation within the outer casing; and c) thefirst driven fitting including a plurality of drive engagement facesdisposed about an axially extending locating member.

In another aspect, the present disclosure relates to a connectionstructure for a flexible shaft drive transmission and a drive motor, theflexible shaft drive transmission transmitting rotational power betweenthe drive motor and a gear train of a power operated tool, theconnection structure comprising: a) the flexible shaft drivetransmission including: i) an elongated drive shaft assembly including arotatable drive transmitting shaft extending along a longitudinal axis,a first driven fitting at one end of the drive transmitting shaft and asecond drive fitting at a second end of the drive transmitting shaft,the first driven fitting and the second drive fitting rotating with thedrive transmitting shaft; ii) an outer casing including first and secondends and defining a throughbore, the outer casing receiving the drivetransmitting shaft within the throughbore and supporting the drivetransmitting shaft for rotation within the outer casing; and iii) amotor end coupling affixed to the first end of the outer casing andadapted to be releasably connected to the drive motor, the motor endcoupling including a coupling body defining a central opening throughwhich the drive transmitting shaft passes and having an outer surfacedefining a tapered region, the tapered region having a proximal end anda distal end, the proximal end of the tapered region of the couplingbody being closer in proximity to the outer casing than the distal endof the tapered region, the tapered region tapering from a first diameterat the proximal end of the tapered region to a second diameter at thedistal end of the tapered region, the first diameter being larger thanthe second diameter; and b) the drive motor including: a drive fittingrotatable about an axis of rotation and a coupling, the couplingincluding a collar, an inner surface of the collar defining an openingconfigured to receive the coupling body of the motor end coupling suchthat the drive fitting of the drive motor operatively engages the drivenfitting of the drive shaft assembly to rotate the drive transmittingshaft within the outer casing of the shaft drive transmission.

In another aspect, the present disclosure relates to a flexible shaftdrive transmission coupled between a drive motor and a gear train of apower operated tool, the flexible shaft drive transmission comprising:a) an outer casing assembly having a drive motor end and a tool end andincluding a bushing positioned at the tool end of the outer casingassembly, the bushing defining a longitudinal central opening; b)lubricant disposed within the outer casing; and c) an elongated drivetransmitting shaft assembly rotatable within the outer casing assembly,the elongated drive transmitting shaft assembly including a flexibledrive transmitting shaft having a motor end and a tool end, the drivetransmitting shaft assembly further including a coupler fitting affixedto the tool end of the drive transmitting shaft, the coupler fittingincluding a body and an enlarged head extending distally from the body,the body fitting within the longitudinal central opening of the bushingand providing a seal between the coupler fitting and the bushing tomitigate leakage of the lubricant from the tool end of the outer casingand the enlarged head having a diameter greater than a diameter of thelongitudinal central opening of the bushing to constrain axial movementof the drive transmitting shaft with respect to the outer casing.

In another aspect, the present disclosure relates to a driver assemblydetachably coupled between a flexible shaft drive transmission having anouter casing and an elongated drive transmitting shaft rotatable withinthe outer casing and a handle assembly of a power operated tool toprovide rotational power from a coupler fitting of the drivetransmitting shaft and a drive train of the power operated rotary knife,the driver assembly comprising: a) a tube assembly comprising a maintube defining a throughbore and first and second bushings disposedwithin the throughbore at respective first and second ends of the maintube and a casing coupler secured to and extending beyond the second endof the main tube, the casing coupler configured to releasably attach thedriver assembly to the outer casing; and b) an elongated shaft supportedfor rotation by the first and second bushings of the tube assembly, afirst end portion of the shaft rotatably supported in the first bushingand a second end portion of the shaft rotatably supported in the secondbushing, the first end portion of the elongated shaft including a driverfitting extending axially beyond the first end of the main tube, thefirst bushing defining an end wall to constrain axial movement of theelongated shaft with respect to the tube assembly in a first direction,the second end portion of the elongated shaft including a driven fittingextending axially beyond the second end of the main tube, the secondbushing including an end wall to constrain axial movement of theelongated shaft with respect to the tube assembly in a directionopposite of the first direction.

In another aspect, the present disclosure relates to a flexible shaftdrive transmission assembly coupled between a drive motor and a geartrain of a power operated tool, the flexible shaft drive transmissionassembly comprising: a) a flexible drive shaft transmissionincluding: 1) an outer casing assembly having a drive motor end and atool end and including a bushing positioned at the tool end of the outercasing assembly, the bushing defining a longitudinal central opening; 2)lubricant disposed within the outer casing; and 3) an elongated drivetransmitting shaft assembly rotatable within the outer casing assembly,the elongated drive transmitting shaft assembly including a flexibledrive transmitting shaft having a motor end and a tool end, the drivetransmitting shaft assembly further including a coupler fitting coupledto the tool end of the drive transmitting shaft, the coupler fittingincluding a body and an enlarged head extending distally from the body,the body fitting within the longitudinal central opening of the bushingand providing a seal between the coupler fitting and the bushing tomitigate leakage of the lubricant from the tool end of the outer casingand the enlarged head having a diameter greater than a diameter of thelongitudinal central opening of the bushing to constrain axial movementof the drive transmitting shaft with respect to the outer casing; and b)a driver assembly including a tube assembly releasably coupled to thetool end of the outer casing assembly and an elongated driver shaftassembly at least partially disposed within the tube assembly andoperatively coupled to coupler fitting of the drive transmitting shaftassembly.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the presentdisclosure will become apparent to one skilled in the art to which thepresent disclosure relates upon consideration of the followingdescription of the disclosure with reference to the accompanyingdrawings, wherein like reference numerals, unless otherwise describedrefer to like parts throughout the drawings and in which:

FIG. 1 is a schematic perspective view of a first exemplary embodimentof a power operated tool assembly, including a power operated rotaryknife, a drive motor assembly, and a flexible shaft drive transmissionof the present disclosure;

FIG. 2 is a schematic exploded perspective view of the power operatedrotary knife of the power operated tool assembly of FIG. 1;

FIG. 2A is a schematic exploded perspective view of a portion of a headassembly of the power operated rotary knife of the power operated toolassembly of FIG. 1 including a rotary knife blade, a blade housing and ablade—blade housing bearing structure that, in one exemplary embodiment,includes an elongated rolling bearing strip that secures and rotatablysupports the rotary knife blade with respect to the blade housing;

FIG. 2B is a schematic exploded perspective view of a handle assembly ofthe power operated rotary knife of the power operated tool assembly ofFIG. 1 including a hand piece, a hand piece retaining assembly and adrive shaft latching assembly supported by the hand piece retainingassembly;

FIG. 2C is a schematic exploded perspective view of a portion of thehead assembly of the power operated rotary knife of the power operatedtool assembly of FIG. 1 including a gearbox assembly, a steelingassembly and a frame body, the gearbox assembly including a gear trainand a gearbox housing;

FIG. 3 is a schematic top plan view of the power operated rotary knifeof the power operated tool assembly FIG. 1;

FIG. 4 is a schematic enlarged section view of the assembled combinationof the rotary knife blade, the blade housing and the blade—blade housingbearing structure of the power operated rotary knife of the poweroperated tool assembly of FIG. 1 as seen from a plane indicated by theline 4-4 in FIG. 3;

FIG. 5 is a schematic side elevation view of the power operated notaryknife of the power operated tool assembly of FIG. 1;

FIG. 6 is a longitudinal sectional view of the power operated rotaryknife of the power operated tool assembly of FIG. 1, as seen from aplane indicated by the line 6-6 in FIG. 3;

FIG. 7 is a schematic view, partly in side elevation and partly insection, of a drive assembly of the power operated tool assembly of FIG.1;

FIG. 8 is a schematic front elevation view of the drive motor assemblyand the shaft drive transmission of the power operated tool assembly ofFIG. 1 with a motor end coupling of the shaft drive transmission and amotor coupling of the drive motor assembly in an engaged state;

FIG. 9 is a schematic side elevation view of the drive motor assemblyand the shaft drive transmission of FIG. 8;

FIG. 10 is a schematic bottom perspective view of the drive motorassembly and the shaft drive transmission of FIG. 8;

FIG. 11 is a schematic perspective view of the drive motor assembly andthe shaft drive transmission of FIG. 8 with an access panel of a drivemotor cover of the drive motor removed to better show the drive motorwithin the drive motor cover;

FIG. 12 is a schematic perspective view of the drive motor assembly,with the drive motor cover removed to better show the drive motor andthe drive motor coupling, and a motor end portion of the flexible shaftdrive transmission of the power operated tool assembly of FIG. 1 in anengaged state;

FIG. 13 is a schematic side elevation view of the drive motor assemblyand the shaft drive transmission of FIG. 12;

FIG. 14A is a schematic exploded perspective view of the drive motorassembly of FIG. 12;

FIG. 14B is a schematic exploded perspective view of a motor end portionof the flexible shaft drive transmission of FIG. 12;

FIG. 15 is a schematic top elevation view of the drive motor assemblyand the shaft drive transmission of FIG. 12;

FIG. 16 is a schematic bottom elevation view of the drive motor assemblyof the power operated tool assembly of FIG. 1, with the flexible shaftdrive transmission removed;

FIG. 17 is a schematic sectional view of the drive motor assembly andthe shaft drive transmission of FIG. 12, as seen from a plane indicatedby the line 17-17 in FIG. 15, showing a drive connection structurebetween a motor end portion of the shaft drive transmission and thedrive motor assembly;

FIG. 18 is a schematic sectional view of the drive motor assembly andthe shaft drive transmission of FIG. 12, as seen from a plane indicatedby the line 18-18 in FIG. 15, showing the drive connection structurebetween a motor end portion of the shaft drive transmission and thedrive motor assembly, with the shaft drive assembly removed for clarity;

FIG. 19 is a schematic side elevation view of the motor end portion ofthe shaft drive transmission of the power operated tool assembly of FIG.1 showing a portion of an outer casing assembly and the drive shaftassembly of the shaft drive transmission;

FIG. 20 is a schematic top plan view of the motor end portion of theshaft drive transmission of FIG. 19;

FIG. 21 is a schematic section view of the motor end portion of theshaft drive transmission of FIG. 19, as seen from a plane indicated bythe line 21-21 in FIG. 20;

FIG. 22 is a schematic side elevation view of a motor end portion of thedrive shaft assembly of the shaft drive transmission of FIG. 19;

FIG. 23 is a schematic section view of the drive shaft assembly of FIG.22, as seen from a plane indicated by the line 23-23 in FIG. 22;

FIG. 24 is a schematic top plan view of the drive shaft assembly of FIG.22, as seen from a plane indicated by the line 24-24 in FIG. 22;

FIG. 25 is a schematic perspective view of a drive connection between adriven fitting of the drive shaft assembly of the shaft drivetransmission and a drive fitting of the drive motor assembly, as theywould appear when the motor end portion of the drive shaft transmissionis in an engaged state with the drive motor assembly; and

FIG. 26 is a schematic front elevation view of drive connectionstructure between a motor end portion of the shaft drive transmissionand the drive motor assembly in an aligned, disengaged state;

FIG. 27 is a schematic front elevation view of drive connectionstructure between a motor end portion of the shaft drive transmissionand the drive motor assembly in a contact, disengaged state;

FIG. 28 is a schematic front elevation view of drive connectionstructure between a motor end portion of the shaft drive transmissionand the drive motor assembly in an engaged state;

FIG. 29 is a schematic perspective view of a second exemplary embodimentof a flexible shaft drive transmission of the present disclosure;

FIG. 30 is a schematic sectional view of a tool end portion of the driveshaft transmission of FIG. 29 in operative engagement or coupled to thehandle assembly of the power operated rotary knife of FIG. 1;

FIG. 31 is a schematic exploded perspective view of the shaft drivetransmission of FIG. 29;

FIG. 32 is a schematic enlarged, exploded perspective view of a portionof the shaft drive transmission of FIG. 29, as would be seen within acircle labeled FIG. 32 in FIG. 31;

FIG. 33 is a schematic sectional view of a power operated rotary knifeend of the shaft drive transmission of FIG. 29 showing a portion of anouter casing assembly and the drive shaft assembly of the shaft drivetransmission, with a driver assembly removed;

FIG. 34 is a schematic side elevation view of the driver assembly of thepower operated rotary knife end of the shaft drive transmission of FIG.29;

FIG. 35 is a schematic exploded perspective view of the driver assemblyof FIG. 34;

FIG. 36 is a schematic longitudinal section view of the driver assemblyof FIG. 34, as seen from a plane indicated by the line 36-36 in FIG. 34;

FIG. 37 is a schematic side elevation view of a coupler screw of thedrive shaft assembly of the shaft drive transmission of FIG. 29;

FIG. 38 is a schematic front elevation view of the coupler screw of FIG.37, as seen from a plane indicated by the line 38-38 in FIG. 37;

FIG. 39 is a schematic longitudinal section view of the coupler screw ofFIG. 37, as seen from a plane indicated by the line 39-39 in FIG. 38;

FIG. 40 is a schematic longitudinal section view of a main tube of thedriver assembly of FIG. 34 of the shaft drive transmission of FIG. 29;

FIG. 41 is a schematic front elevation view of a driver fitting of thedriver assembly of FIG. 34 the shaft drive transmission of FIG. 29;

FIG. 42 is a schematic longitudinal section view of the driver fittingof FIG. 41, as seen from a plane indicated by the line 42-42 in FIG. 41;

FIG. 43 is a schematic side elevation view of a casing coupler of thedriver assembly of FIG. 34 of the shaft drive transmission of FIG. 29;

FIG. 44 is a schematic front elevation view of the casing coupler ofFIG. 43; and

FIG. 45 is a longitudinal section view of the casing coupler of FIG. 43,as seen from a plane indicated by the line 45-45 in FIG. 44.

DETAILED DESCRIPTION

The present disclosure relates to a drive interface or drive connectionstructure, shown generally at 1000 in FIGS. 8-13, for operativelycoupling a flexible shaft drive transmission 700 and an external drivemotor assembly 900 for transmitting motive or rotational power from adrive motor 901 of the drive motor assembly 900 to a power operated tool100, such as a power operated rotary knife. The shaft drivetransmission-drive motor drive connection structure 1000 includes amotor end coupling 714 and a driven fitting 814 of the flexible shaftdrive transmission 700 and a drive motor coupling 915 and a drivefitting 972 of the drive motor assembly 900. The motor end coupling 714of the flexible shaft drive transmission 700 is configured to releasablyengage the drive motor coupling 915 of the drive motor assembly 900.When the motor end coupling 714 is operatively engaged or is in anengaged state with respect to the drive motor coupling 915, the drivenfitting 814 is operatively engaged by or coupled to the drive fitting972 of the drive motor assembly 900. The driven fitting 814 is part of adrive shaft assembly 800 of the flexible shaft drive transmission 700.The drive shaft assembly 800 includes an elongated, flexible drivetransmitting shaft or flex shaft 802, the driven fitting 814 at a firstend 810 of the drive shaft assembly 800, and a male drive fitting 884 ata second end 880 of the drive shaft assembly 800.

Advantageously, the drive connection structure 1000 of the presentdisclosure provides for quick coupling and uncoupling of mating motorend and drive motor couplings 714, 915 of the flexible shaft drivetransmission 700 and the drive motor assembly 900 by an operator of thepower operated tool 100 using one hand. Additionally, when the couplings714, 915 of the shaft drive transmission 700 and the drive motorassembly 900 are in the engaged state, in one exemplary embodiment ofthe present disclosure, a drive engagement structure 1002 (FIG. 25)between the driven fitting 814 of the shaft drive transmission 700 andthe drive fitting 972 of the drive motor assembly 900 comprises aplurality of planar drive engagement surfaces 832, 984. As can best beseen in FIGS. 22 and 25, the planar drive engagement surfaces 832 of thedriven fitting 814 are defined on or are formed on axially projectingvanes 830 of the driven fitting 814. As can best be seen in FIGS. 25 and26, the planar drive engagement surfaces 984 of the drive fitting 972are defined on or are formed on axially projecting vanes 982 of thedrive fitting 972.

The drive engagement structure 1002 of the present disclosure alsoincludes an axial locating structure 1004. The planar drive engagementsurfaces 832 of the plurality of vanes 830 of the driven fitting 814extend radially about a locating member 822 of the driven fitting 814.Similarly, the planar drive engagement surfaces 984 of the drive fitting972 extend radially about a locating member 992 of the drive fitting972. In one exemplary embodiment, the locating member 822 of the drivefitting 814 comprises a tapered central projection 824 and the locatingmember 992 of the drive fitting 972 comprises a tapered central opening994 in the drive fitting 972. When the motor end coupling 714 of theflexible shaft drive transmission 700 and the drive motor coupling 915of the drive motor assembly 900 are in the engaged state, the taperedcentral projection 824 of the driven fitting 814 is received into thetapered central opening 994 of the drive fitting 972 to define the axiallocating structure 1004.

Advantageously, the drive engagement structure 1002 of the presentdisclosure comprising the plurality of planar drive engagement surfaces832, 984 of the driven and drive fitting fittings 814, 972 provides alarge drive or contact area between the fittings 814, 972 resulting in adurable, positive drive connection between the drive motor 901 and theflex shaft 802 of the shaft drive transmission 700. Furthermore, theaxial locating structure 1004 of the present disclosure comprising thecentral locating member 822 of the driven fitting 814 and the centralopening 984 of the drive fitting 972 advantageously provides foraccurate alignment of an axis of rotation RMD of a drive shaft 970 ofthe drive motor 901 and an axis of rotation RFS of the drivetransmitting shaft or flex shaft 802 of the drive shaft assembly 800.Moreover, the drive connection structure 1000 of the present disclosureeliminates the need for a rotatable or slip ring interposed between themating couplings 714, 915 of the shaft drive transmission 700 and thedrive motor assembly 900.

In one exemplary embodiment, the present disclosure features a poweroperated tool assembly 10 including: the power operated tool 100, suchas a power operated rotary knife; the external drive motor assembly 900;and the flexible shaft drive transmission 700 extending between andtransmitting motive or rotational drive power between the drive motor901 of the drive motor assembly 900 and the power operated rotary knife100. The flexible shaft drive transmission 700, the drive motor 901 andthe drive motor coupling 915 of the drive motor assembly 900 are part ofa drive mechanism or assembly 600 of the power operated tool assembly 10that operably connects rotational power generated by the drive motor 900to the power operated rotary knife 100 to rotate a rotary knife blade300 of the rotary knife 100.

The flexible shaft drive transmission 700 includes an outer casingassembly 702 and the drive shaft assembly 800, which is rotatable withinthe outer casing assembly 702. The outer casing assembly 702 includes alongitudinally extending, generally tubular outer casing 704 whichdefines a tubular throughbore 706. The outer casing assembly 702additionally includes the first or motor end coupling 714 disposed at afirst end 710 of the outer casing 704 and a second or handle assemblycoupling 784 disposed at a second end 780 of the outer casing 704. Themotor end coupling 714 and the handle assembly coupling 784 each includecentral openings or passageways that continue the throughbore 706 of theouter casing 704 such that the drive shaft assembly 800 extends throughthe throughbore 706 and beyond respective ends of the motor end coupling714 and the handle assembly coupling 784. The motor end or motorcoupling 714 is configured to be releasably coupled to the drive motorcoupling 915 of the drive motor assembly 900 and the handle assemblycoupling 784 is configured to be releasably coupled to the handleassembly 110 of the power operated rotary knife 100 to transmit motivepower or drive torque from the drive motor 900 to the power operatedrotary knife 100.

The drive shaft assembly 800 includes the flexible, elongated drivetransmitting shaft or flex shaft 802 extending through the outer casing704 and includes the first, driven fitting 814 disposed at the first endof 810 of the flex shaft 802 and the second, male drive fitting 884disposed at the second end 880 of the flex shaft 802. The outer casing704 surrounds and is coaxial with the flex shaft 802. To reduce frictionbetween the rotating flex shaft 802 and the stationary outer casing 704,a relatively viscous lubricant (not shown) is disposed within the outercasing 704. The drive transmitting shaft or flex shaft 802 comprises asolid, steel central core 804 which, in one exemplary embodiment, is acentral wire surrounded by one or more layers of wires or windingstightly wrapped around the core wire 804 in a helix. The flex shaft 802is capable of transmitting substantial torque yet is flexible so thatthe power operated rotary knife 100 can be manipulated while drive istransmitting to and through it. The flex shaft 802 is freely rotatablewith respect to the casing assembly 702, including the outer casing 704and the motor end and handle assembly couplings 714, 784.

The driven fitting 814 of the drive shaft assembly 800 is engaged androtated by the mating drive fitting 972 of the drive motor assembly 900when the first or motor end coupling 714 is operatively coupled orengaged to the motor coupling 915 of the drive motor assembly 900 andthe drive motor 901 is actuated. The drive fitting 884 of the driveshaft assembly 800 engages and rotates a female socket for fitting 622of a pinion gear 610 of the power operated rotary knife 100 when thehandle assembly coupling 784 is operatively coupled or engaged to thehandle assembly 110 of the power operated rotary knife 100 and the drivemotor is actuated.

Power Operated Rotary Knife 100

In one exemplary embodiment, the power operated tool 100 comprises apower operated rotary knife, as shown in FIGS. 1-6. The power operatedrotary knife 100 includes an elongated handle assembly 110 and a headassembly or head portion 111 removably coupled to a forward end of thehandle assembly 110. The handle assembly 110 includes a hand piece 200that is secured to the head assembly 111 by a hand piece retainingassembly 250 (FIGS. 2 and 2B).

In one exemplary embodiment, the head assembly 1 includes a continuous,generally ring-shaped or annular rotary knife blade 300, a continuous,generally ring shaped or annular blade housing 400, and a blade—bladehousing support or bearing structure 500. Annular, as used herein, meansgenerally ring-like or generally ring-shaped in configuration.Continuous annular, as used herein, means a ring-like or ring-shapeconfiguration that is continuous about the ring or annulus, that is, thering or annulus does not include a split extending through a diameter ofthe ring or annulus. The head assembly 111 further includes a gearboxassembly 112 and a frame or frame body 150 for securing the rotary knifeblade 300 and the blade housing 400 to the gearbox assembly 112.

The rotary knife blade 300 rotates in the blade housing 400 about itsaxis of rotation R. In one exemplary embodiment, the rotary knife blade300 includes a bearing surface 319 and the driven gear 328. Both thebearing surface 319 and the driven gear 328 are axially spaced from anupper end 306 of a body 302 of the blade 300 and from each other. Therotary knife blade 300 is supported for rotation in the blade housing400 by the blade—blade housing support or bearing structure 500 of thepresent disclosure (best seen in FIG. 4). The blade—blade housingbearing structure 500 both supports the rotary knife blade 300 forrotation with respect to the blade housing 400 and releasably securesthe rotary knife blade 300 to the blade housing 400.

In one exemplary embodiment, the blade—blade housing bearing structure500 includes an elongated rolling bearing strip 502 having a pluralityof spaced apart rolling bearings such as a plurality of ball bearings506 supported in a flexible separator cage 508. The elongated rollingbearing strip 502 is disposed in an annular passageway 504 (FIG. 4)formed between opposing bearing surfaces 319, 459 of the rotary knifeblade 300 and the blade housing 400, respectfully. The blade—bladehousing bearing structure 500 defines a plane of rotation RP (FIGS. 5and 6) of the rotary knife blade 300 with respect to the blade housing400, the rotational plane RP being substantially orthogonal to therotary knife blade central axis of rotation R.

The plurality of ball or rolling bearings 506 are in rolling contactwith and bear against the opposing bearing surfaces 319, 459 of therotary knife blade 300 and the blade housing 400 to support the knifeblade 300 for rotation with respect to the blade housing 400 and securethe knife blade 300 with respect to the blade housing 400. The flexibleseparator cage 508 rotatably supports and locates the plurality ofrolling bearings 506 in spaced apart relation within the annularpassageway 504. As can best be seen in FIG. 2, an assembled combination550 of the rotary knife blade 300, the blade housing 400 and blade—bladehousing bearing structure 500 is releasably secured as a unitarystructure to the gearbox assembly 112 by the frame body 150 therebycompleting the head assembly 111. The assembled combination 550 of therotary knife blade 300, the blade housing 400 and blade—blade housingbearing structure 500 is referred to as the blade—blade housingcombination 550. The handle assembly 110 is releasably secured to thehead assembly 111 by the hand piece retaining assembly 250 (FIG. 2B)thereby completing the power operated rotary knife 100. As used hereinwith respect to the power operated rotary knife 100, as shown in FIGS.2-6, a front or distal end of the power operated rotary knife 100 is anend of the knife 100 that includes the blade—blade housing combination550 (as seen in FIG. 2), while a rear or proximal end of the poweroperated rotary knife 100 is an end of the knife 100 that includes thehandle assembly 110, and, specifically, an enlarged end 260 of anelongated central core 252 of the hand piece retaining assembly 250.

The rotational speed of a specific rotary knife blade 300 in the poweroperated rotary knife 100 will depend upon the specific characteristicsof the drive mechanism 600 (shown schematically in FIG. 7) of the poweroperated tool assembly 10, including the external drive motor 901, thedrive motor coupling 915, the flexible shaft drive assembly 700, thegear train 604, and a diameter and gearing of the rotary knife blade300. Further, depending on the cutting or trimming task to be performed,different sizes and styles of rotary knife blades may be utilized in thepower operated rotary knife 100 of the present disclosure. For example,rotary knife blades in various diameters are typically offered rangingin size from around 1.4 inches in diameter to over 7 inches in diameter.Selection of a blade diameter will depend on the task or tasks beingperformed.

The head assembly 111 includes the frame 150 and the gearbox assembly112. As is best seen in FIG. 2C, the gearbox assembly 112 includes agearbox housing 113 and the gear train 604. The gear train 604 issupported by the gearbox housing 113. The gear train 604 includes, inone exemplary embodiment, the pinion gear 610 and a drive gear 650,together with a bearing support assembly 630 that rotatably supports thepinion gear 610 and a bearing support assembly 660 that rotatablysupports the drive gear 650.

The pinion gear 610 comprises an input shaft 612 and a gear head 614that extends radially outwardly from the input shaft 612 and defines aset of bevel gear teeth 616. The input shaft 612 extends in a rearwarddirection RW along the handle assembly longitudinal axis IA and includesa central opening 618 (FIG. 6) extending in a forward direction FW froma rearward end 629 (FIG. 2C) to a forward end 628 of the input shaft612, the central opening 618 terminating at the gear head 614. An innersurface 620 of the input shaft 612 defines the cross-shaped femalesocket or fitting 622 (FIG. 6) which receives a mating male drivefitting 814 (FIG. 1) of the flexible shaft drive transmission 700 torotate the pinion gear 610 about an axis of rotation PGR which issubstantially congruent with the handle assembly longitudinal axis LAand intersects the knife blade axis of rotation R. The pinion gear 610is supported for rotation in the gearbox housing 113 by a pair of sleevebushings 632, 640 (FIG. 2C).

The drive gear 650 is a double gear that includes a first bevel gear 652and a second spur gear 654, disposed in a stacked relationship, about anaxis of rotation DGR (FIG. 7) of the drive gear 650. The drive gear axisof rotation DRG is substantially parallel to the rotary knife blade axisof rotation R. The drive gear first bevel gear 652 meshes with thepinion gear 610 to rotatably drive the drive gear 650 about the drivegear axis of rotation DGR. The second spur gear 654 of the drive gearengages the driven gear 328 of the rotary knife blade 300, forming aninvolute gear drive, to rotate the knife blade 300 about the blade axisof rotation R. The drive gear 650 is supported for rotation in thegearbox housing 113 by a ball bearing assembly 662.

The gear train 604 is part of the drive mechanism 600 (shownschematically in FIG. 7), some of which is external to the poweroperated rotary knife 100, that provides motive power to rotate therotary knife blade 300 with respect to the blade housing 400. The drivemechanism 600 includes the external drive motor assembly 900 and theflexible shaft drive assembly 700, which is releasably secured to thehandle assembly 110 by a drive shaft latching assembly 275 (FIG. 2B).The drive shaft latching assembly 275 is supported in the enlarged end260 of the elongated central care 252. Specifically, a slidable latch276 is constrained in U-shaped slot 268 extending partially through theenlarged end 260 of the elongated central core 252. An inner peripheralportion 277 of a slidable latch 276 (FIG. 2B) of the latching assembly275 is biased by a pair of springs 278 to engage a radial securementgroove 788 (FIG. 1) of the handle assembly coupling 780 of the driveshaft assembly 800. The latch 276 releasably secures the handle assemblycoupling 780 to the central core 252 of the handle assembly 110. Whenthe handle assembly coupling 780 is coupled to the handle assemblycentral core 252, the male drive fitting 884 of the drive shaft assembly800 engages the mating female socket or fitting 622 of the pinion gear610 of the power operated rotary knife 100.

The inner surface 254 of the elongated central core 252 also includes aninwardly stepped shoulder 266 (FIG. 6) that provides a stop for acorresponding outwardly stepped shoulder 794 of the handle assemblycoupling 784 of the flexible shaft drive transmission 700. A radiallyextending shoulder 265 (FIG. 2B) of an outer surface 256 of central core252 serves as a stop for an interfitting radially inwardly steppedshoulder 218 of the inner surface 201 of hand piece 200 to secure thehand piece 200 in place with respect to the head assembly 111. The geartrain 604 of the power operated rotary knife 100 transmits rotationalpower from a flexible elongated drive transmitting shaft or flex shaft802 of the flexible shaft drive assembly 700, through the pinion anddrive gears 610, 650, to rotate the rotary knife blade 300 with respectto the blade housing 400.

The frame body 150 (FIG. 2C) of the head assembly 111 includes anarcuate mounting pedestal 152 at a front or forward end 151 of the framebody 150. The arcuate mounting pedestal 152 defines a sealing region 152a for a mounting section 402 of the blade housing 400 such that theblade—blade housing combination 550 may be releasably affixed to theframe body 150. The frame body 150 also defines a cavity or opening thatslidably receives the gearbox housing 113, as the gearbox housing ismoved in a forward direction FW (FIG. 3) along a longitudinal axis LA ofthe handle assembly 110 in the direction of the frame body 150. When thegearbox housing 113 is fully inserted into the frame cavity and securedto the frame body 150 by a pair of threaded fasteners 192 (FIG. 2C), thedrive gear 650 of the gear train 604 engages and meshes with the drivengear 328 of the rotary knife blade 300 to rotate the blade 300 about itsaxis of rotation R.

The frame body 150 releasably couples the blade—blade housingcombination 550 to the gearbox housing 113 to form the head assembly 111of the power operated rotary knife 100. The hand piece 200 of the handleassembly 110 is secured or mounted to the head assembly 111 by the handpiece retaining assembly 250 (FIG. 2B) to complete the power operatedrotary knife 100. The elongated central core 252 of the hand pieceretaining assembly 250 extends through a central throughbore 202 of thehand piece 200 and threads into the gearbox housing 113 to secure thehand piece 200 to the gearbox housing 113.

The handle assembly 110 (FIG. 2B) extends along the longitudinal axis LA(FIGS. 3, 5 and 6) of the handle assembly 110 that is substantiallyorthogonal to the central axis of rotation R of the rotary knife blade300. The hand piece 200 includes an inner surface 201 that defines thecentral throughbore 202, which extends along the handle assemblylongitudinal axis LA. The hand piece 200 includes a contoured outerhandle or outer gripping surface 204 that is grasped by an operator toappropriately manipulate the power operated rotary knife 100 fortrimming and cutting operations. As can be seen in FIG. 6, the handpiece retaining assembly 250 includes the elongated central core 252having a threaded portion 262 on a reduced diameter end 264. To securethe hand piece 200 to the head assembly 111, the central core 252 isaligned and rotated such that the threaded portion 262 is screwed into athreaded opening 149 of the gearbox housing 113.

In one exemplary embodiment, the rotary knife blade 300 of the poweroperated rotary knife 100 is a one-piece, continuous annular structure.As can best be seen in FIG. 4, the rotary knife blade 300 includes thebody 302 and a blade section 304 extending axially from the body 302.The knife blade body 302 includes an upper end 306 and a lower end 308spaced axially from the upper end 306. The body 302 of the rotary knifeblade 300 further includes an inner wall 310 and an outer wall 312spaced radially apart from the inner wall 310. An upper, substantiallyvertical portion 340 of the body outer wall 312 defines the knife bladebearing surface 319. In one exemplary embodiment of the power operatedrotary knife 100 and as best seen in FIG. 4, the knife blade bearingsurface 319 comprises a bearing race 320 that is arcuate in a centralportion and extends radially inwardly into the outer wall 312. As can beseen in FIG. 4, the knife blade bearing race 320 is axially spaced fromthe upper end 306 of the knife blade body 302.

The outer wall 312 of the body 302 of the rotary knife blade 300 definesthe driven gear 328. The driven gear 328 comprises the set of spur gearteeth 330 extending radially outwardly in a stepped portion of the outerwall 312. In one exemplary embodiment, the blade driven gear 328 is aspur gear which means that it is a cylindrical gear defining a set ofgear teeth 330 that are parallel to the axis of the gear, i.e., parallelto the axis of rotation R of the rotary knife blade 300. The set of spurgear teeth 330 of the knife blade driven gear 328 are axially spacedfrom both the upper end 306 of the body 302 and the lower end 308 of thebody 302 and are axially spaced from the arcuate bearing race 320 of thebody 302.

The blade section 304 extends from the second end 308 of the body 302and includes a blade cutting edge 350 at an inner, lower end 352 of theblade section 304. As can be seen, the blade section 304 includes aninner wall 354 and a radially spaced apart outer wall 356. The inner andouter walls 354, 356 are substantially parallel. A bridging portion 358at the forward end of the rotary knife blade 300 extends between theinner and outer walls 354, 356 and forms the cutting edge 350 at theintersection of the bridging portion 358 and the inner wall 354. As canbest be seen in FIG. 4, the rotary knife blade body inner wall 310 andthe blade section inner wall 354 together form a substantiallycontinuous knife blade inner wall 360 that extends from the upper end306 to the cutting edge 350. The knife blade inner wall 360 defines acutting opening CO (FIGS. 1 and 3) of the power operated rotary knife100, that is, the opening defined by the rotary knife blade 300 that cutmaterial passes through, as the power operated rotary knife 100 trims orcut a product.

In one exemplary embodiment, the blade housing 400 of the power operatedrotary knife 100 is a one-piece, continuous annular structure. The bladehousing 400 includes the mounting section 402 and a blade supportsection 450 extending from the mounting section 402. In the bladehousing 400, the blade support section extends around the entire 360degrees (360°) circumference of the blade housing 400. The mountingsection 402 extends radially outwardly from the blade support section450 and subtends an angle of approximately 120°. Stated another way, theblade housing mounting section 402 extends approximately ⅓ of the wayaround the circumference of the blade housing 400. In the region of themounting section 402, the mounting section 402 and the blade supportsection 450 overlap.

The mounting section 402 is both axially thicker and radially wider thanthe blade support section 450. The blade housing mounting section 402includes an inner wall 404 and a radially spaced apart outer wall 406and a first upper end 408 and an axially spaced apart second lower end410. At forward ends 412, 414 of the mounting section 402, there aretapered regions that transition between the upper end 408, lower end 410and outer wall 406 of the mounting section and the corresponding upperend, lower end and outer wall of the blade support section 450.

The blade housing mounting section 402 includes two mounting inserts420, 422 (FIG. 2A) that extend between the upper and lower ends 408, 410of the mounting section 402. The mounting inserts 420 define threadedopenings 422 (FIG. 2A). The blade housing mounting section 402 isreceived in the seating region 152 a defined by the arcuate mountingpedestal 152 of the frame body 150 and is secured to the frame body 150by a pair of threaded fasteners 170 (FIG. 2C). Specifically, the pair ofthreaded fasteners 170 extend through threaded openings 160 a, 162 adefined in a pair of arcuate arms 160, 162 of the frame body 150 andthread into the threaded openings 422 of the blade housing mountinginserts 420 to releasably secure the blade housing 400 to the frame body150 and, thereby, couple the blade housing 400 to the gearbox assembly112 of the head assembly 111.

The mounting section 402 further includes a gearing recess 424 (FIG. 2A)that extends radially between the inner and outer walls 404, 406. Thegearing recess 424 includes an upper clearance recess 426 that does notextend all the way to the inner wall and a wider lower opening 428 thatextends between and through the inner and outer walls 404, 406. Theupper clearance recess 426 provides clearance for the pinion gear 610and the axially oriented rust bevel gear 652 of the gearbox drive gear650. The lower opening 428 is sized to receive the radially extendingsecond spur gear 654 of the gearbox drive gear 650 and thereby providefor the interface or meshing of the second spur gear 654 and the drivengear 328 of the rotary knife blade 300 to rotate the knife blade 300with respect to the blade housing 400.

The mounting section 402 of the blade housing 400 also includes a bladehousing plug opening 429 (FIG. 2A) extending between the inner and outerwalls 404, 406. The blade housing plug opening 429 is generallyoval-shaped in cross section and is sized to receive a blade housingplug 430. The blade housing plug 430 is removably secured to the bladehousing 400 by two screws 432 (FIG. 2A). Removal of the blade housingplug 430 allows for the rolling bearing strip 502 of the blade—bladehousing bearing structure 500 to be threaded into the annular passageway504 to rotatably secure the rotary knife blade 300 to the blade housing400 and to be removed from the annular passageway 504 to allow the knifeblade 300 to be removed from the blade housing 400.

In one exemplary embodiment of the power operated rotary knife 100 andas best seen in FIG. 4, the blade housing bearing surface 459 comprisesa bearing race 460 that extends radially inwardly into the inner wall452. The bearing race 460 is arcuate in a central portion of the bearingrace 460. The bearing race 460 is axially spaced from the upper end 456of the blade support section 450.

A forward wall 154 a of a central cylindrical region 154 of the framebody 150 includes a projection 198 that supports a steeling assembly 199(FIG. 2C). The steeling assembly 199 includes a support body 199 a,spring biased actuator 199 b, and a push rod 199 c with a steelingmember 199 d affixed to a bottom of the push rod 199 c. The steelingassembly support body 199 a is affixed to the projection 198. When theactuator 199 b is depressed by the operator, the push rod 199 c movesdownwardly and the steeling member 199 d engages the blade edge 350 ofthe knife blade 300 to straighten the blade edge 350.

In one exemplary embodiment, the hand piece 200 and the elongatedcentral core 252 of the handle assembly 110 may be fabricated of plasticor other material or materials known to have comparable properties andmay be formed by molding and/or machining. The hand piece 200, forexample, may be fabricated of two over molded plastic layers, an innerlayer comprising a hard plastic material and an outer layer or grippingsurface comprised of a softer, resilient plastic material that is morepliable and easier to grip for the operator. The gearbox housing 113 andthe frame body 150 of the head assembly 111 may be fabricated ofaluminum or stainless steel or other material or materials known to havecomparable properties and may be formed/shaped by casting and/ormachining. The blade and blade housing 400 may be fabricated of ahardenable grade of alloy steel or a hardenable grade of stainlesssteel, or other material or materials known to have comparableproperties and may be formed/shaped by machining, forming, casting,forging, extrusion, metal injection molding, and/or electrical dischargemachining or another suitable process or combination of processes.Additional details regarding the structure and function of the poweroperated rotary knife 100 are found in the previously referenced '951application, which is incorporated herein in its entirety.

Flexible Shaft Drive Transmission 700

As can best be seen in FIGS. 1, 19-21, the flexible shaft drivetransmission 700 comprises the outer casing assembly 702 and the driveshaft assembly 800, which is rotatably supported within the tubularthroughbore 706 defined by the outer casing 704. The outer casingassembly 702 is stationary with respect to the rotating drive shaftassembly 800 and includes the outer casing 704, the motor end coupling714 and the handle assembly coupling 784. The outer casing assembly 702includes an outer casing 704 comprising a flexible tube. The flexibletube may include one or more tubular layers of plastic material, such asnylon, and, optionally, also may include one or more layers of braidedwire between the tubular layers for added strength and durability. Oneor more layers may optionally comprise a spiral wound layer of metalconduit with interlocking edges, as disclosed in U.S. publishedapplication no. US-2007-0078012-A1, published Apr. 5, 2007.

The drive shaft assembly 800 includes the drive transmitting shaft orflex shaft 802, the first, driven fitting 814 at the first end 810 ofthe flex shaft 802 and the second, male drive fitting 884 at the secondend 880 of the flex shaft 802. When the motor end coupling 714 of thedrive shaft assembly 800 is in the engaged state (operatively coupled orconnected) to the motor coupling 915 of the drive motor assembly 900 (asshown, for example, in FIGS. 8-13), the first, driven fitting 814 isoperatively engaged with the drive fitting 972 of the drive motorassembly 900, as shown in FIG. 25. Actuation of the drive motor 901,when the motor end coupling 714 and the drive motor coupling 915 are inthe engaged state results in rotation of the flex shaft 802 and, via thegear train 604, rotation of the rotary knife blade 300 of the poweroperated rotary knife 100.

The flexible shaft drive transmission 700 includes a first end 701 a,adjacent the drive motor assembly 900, a second end 701 b, adjacent thepower operated rotary knife handle assembly 110, and a flexible,elongated central portion 701 c. When driven by the drive motor assembly900, the flex shaft 802 of the drive shaft assembly 800 rotates about anaxis of rotation RFS (FIGS. 1, 19, 21 and 22), which is substantiallycongruent with a central longitudinal axis LASDT of the drive shaftassembly 800. The central longitudinal axis LASDT of the drive shaftassembly 800 is substantially congruent with a center line CLFS (FIG.22) though the flex shaft 802 and also defines a central longitudinalaxis of the flexible shaft drive transmission 700.

When the handle assembly coupling 784 of the outer casing assembly 702is coupled to the central core 252 of the handle assembly 110 by thedrive shaft latching assembly 275, the male drive fitting 884 of thedrive shaft assembly 800 operatively engages the female fitting 622 ofthe pinion gear 610. When the handle assembly coupling 784 is connectedto the handle assembly 110, the central longitudinal axis LASDT of thedrive shaft assembly 800 is substantially congruent with both the piniongear axis of rotation PGR and the longitudinal axis LA of the handleassembly 110.

When the motor end coupling 714 of the outer casing assembly 702 iscoupled to or in an engaged state with the motor coupling 915 of thedrive motor assembly 900, the drive fitting 972 of the drive motor 901operatively engages the driven fitting 814 of the drive shaft assembly800 and the central longitudinal axis LASDT of the drive shaft assembly800 is substantially congruent with an axis of rotation RMD (FIG. 18) ofthe drive motor 901 and is substantially congruent with a center lineCLMDS through a drive shaft 970 of the drive motor 901. As used hereinwith respect to the drive connection structure 1000 of the flexibleshaft drive transmission 700 and the drive motor assembly 900, the termaxial shall mean in a direction or movement along the centrallongitudinal axis LASDT of the drive shaft assembly 800, while the termradial shall mean movement in a direction radially away or outwardlyfrom the central longitudinal axis LASDT.

As can best be seen in FIGS. 19 and 21, the flex shaft 802 of the shaftdrive transmission 800 extends through the throughbore 706 defined bythe tubular outer casing 704 and through a throughbore 716 of the motorend coupling 714. The driven fitting 814 of the drive shaft assembly 800extends distally beyond the motor end coupling 714. As used herein, withrespect to the motor end 701 a of the flexible shaft drive transmission700, the terms distal or distal direction DISTRAN (FIGS. 17-19) shallmean in a direction from the central portion 701 c of the shaft drivetransmission 700 toward the first, motor end portion 701 a of the shaftdrive transmission 700 and toward the drive motor 900. The termsproximal or proximal direction PRXTRAN shall mean the oppositedirection. That is, as can be seen in FIG. 19, the driven fitting 814 ofthe shaft drive assembly 800 is distal or in the distal directionDISTRAN with respect to the motor end coupling 714, while the outercasing 704 is proximal or in the proximal direction PRXTRAN with respectto the driven fitting 814 and the motor end coupling 714.

The motor end coupling 714 includes a coupling body 720 and a supportpedestal 750 which supports the coupling body 720 and attaches orsecures the coupling body 720 to the outer casing 704 of the outercasing assembly 702. As can best be seen in FIGS. 19-21, the couplingbody 720 is generally cone-shaped or frustoconical shaped and includesan outer surface 721 and an inner surface 722. The inner surface 722defines a central opening 723 which is part of the throughbore 716 ofthe motor end coupling 714. As can best be seen in FIGS. 14B, 19 and 21,the coupling body 720 includes a distal tapered region 727 and aproximal generally cylindrical region 730. The distal tapered region 727defines a distal end 729 of the coupling body 720, while the proximalcylindrical region 730 defines a proximal end 728 of the coupling body720. The distal end 729 of the coupling body 720 is defined by a distalend wall 746 of the coupling body 720, while the proximal end 728 of thecoupling body 720 is defined by a proximal end wall 744.

As can be seen in FIG. 19, an outer diameter ODPRX at a proximal end 742of the distal tapered region 727 of the coupling body 720 is larger thanan outer diameter ODDIS at a distal end 743 of the distal tapered region727 of the coupling body 720. The distal end 743 of the distal taperedregion 727 coincides with the distal end 729 of the coupling body 720.The proximal end 742 of the distal tapered region 727 approximatelycoincides with a proximal end 740 (FIG. 19) of a plurality of channelsor recesses 740 formed in the outer surface 721 of the coupling body720. The tapering between the proximal and distal ends 742, 743 of thetapered distal region 727 is a substantially a uniform taper resultingin the coupling body 720 having the configuration of a substantiallyfrustoconical, tapered cone 732. In one exemplary embodiment, an angleof taper of the cone 732 is approximately 10° with respect to the shaftdrive transmission central longitudinal axis LASDT.

In the tapered distal region 727 of the coupling body 720, the outersurface 721 of the coupling body 720 defines a plurality of radiallyspaced apart raised ribs 734 separated by the plurality of channels orrecesses 740 between the ribs 734. The ribs 734 extend axially orlongitudinally along the tapered central region 726 of the coupling body720. In one exemplary embodiment, the number of raised ribs 734 andchannels 740 is six. In one exemplary embodiment, because the tapereddistal region 727 is generally uniformly tapered from a larger diameterproximal end 742 to a small diameter distal end 743, both the raisedribs 734 and the channels 740 taper uniformly from a narrower distal end734 b, 740 b to a wider at a proximal end 734 a, 740 a. That is, acircumferential distance or are defined by each of the ribs 734 andchannels 740 increases when proceeding from the distal end 743 to theproximal end 742 of the tapered distal region 727 of the coupling body720. Additionally, in one exemplary embodiment, each of the raised ribs734 is of substantially uniform height above the respective adjacentchannels 740 from the distal end 734 b to the proximal end 734 a of therib 734.

The plurality of ribs 734 of the tapered distal region 727 of thecoupling body 720 are configured to interfit with a plurality ofchannels or recesses 957 of the mating tapered collar 950 of the drivemotor coupling 915, while the plurality of channels 740 of the tapereddistal region 727 of the coupling body 720 are configured to interfitwith a plurality of raised ribs 956 of the tapered collar 950 of thedrive motor coupling 915. In one exemplary embodiment, each of thechannels 957 and the ribs 956 of the tapered collar 950 are taperedalong their longitudinal extent, like the ribs 734 and channels 740 ofthe coupling body 720, to properly receive the tapered ribs 734 and thetapered channels 740 of the tapered distal region 727 of the couplingbody 720.

The tapered, mating configurations of the respective six recesses 734,957 and six ribs 734, 956 of the coupling body 720 of the motor endcoupling 714 and the tapered collar 950 of the motor drive coupling 915advantageously allows for easy, one handed insertion of the couplingbody 720 into the tapered collar 950. Moreover, the use of theinterfitting tapered couplings 714, 915, with six recesses and sixinterfitting ribs, results in positive and sure alignment of the drivemotor rotational axis RMD and the flex shaft axis of rotation RFS andthe central longitudinal axis LASDT of the flexible shaft drivetransmission 700. As explained previously, properly alignment of theaxis of rotation RMD of the drive motor 901 and the axis of rotation RFSof the drive transmitting shaft or flex shaft 802 is important inreducing flex shaft vibration and excessive wearing of components of theshaft drive transmission 700.

As can best be seen in FIGS. 14B and 21, the central opening 723 of thecoupling body 720 includes a smaller diameter upper portion 724 and alarger diameter lower portion 725. A shoulder 726 is formed between theupper and lower portions 724, 725 of the coupling body 720.

The motor end coupling 714 also includes the support pedestal 750. Ascan best be seen in FIGS. 14 and 21, the support pedestal 750 includesan outer surface 752 and an inner surface 754. The inner surface 754defines a longitudinal passageway or central opening 755 which defines aportion of the throughbore 716 of the motor end coupling 714. Thesupport pedestal 750 includes a distal, axially thicker walled,cylindrical stem portion 760 and a proximal, axially thinner walled,cylindrical casing portion 762. The stem portion 760 of the supportpedestal 750 is received into the central opening 723 and supports thecoupling body 720. A stepped shoulder 763 is formed on the outer surface752 between the stem portion 760 and the casing portion 762 of thesupport pedestal 750. The stepped shoulder 763 of the support pedestal750 engages the stepped shoulder 726 of the coupling body 720 to inhibitaxial movement of the coupling body 720 in the proximal directionPRXTRAN.

An upper or distal portion 764 of the stem 760 extends distally beyondthe distal end 729 of the coupling body 720. The distal portion 764 ofthe stem 760 includes a circumferential groove 767 formed in the outersurface 752. The groove 767 receives a retaining ring 776 to inhibitaxial movement of the coupling body 720 in the distal direction DISTRANwith respect to the support pedestal 750. Relative rotational movementof the coupling body 720 with respect to the support pedestal 750 byengagement of a knurled peripheral annulus 768 formed on the outersurface 752 of the support pedestal 750 and an aligned knurledperipheral annular 747 formed on the inner surface 722 of the couplingbody 720.

A sleeve bushing 770 is disposed at a distal end 766 of the supportpedestal stem portion 760. In one exemplary embodiment, the sleevebushing 770 is pressed into the upper, reduced diameter portion 756 ofthe central opening 755 of the support pedestal 750. The sleeve bushing770 includes an enlarged annular head 771 and a cylindrical body 772. Asnoted above, the cylindrical body 772 of the bushing 770 is received inthe upper reduced diameter portion 756 of the support pedestallongitudinal passageway 755 and a proximal wall 774 defined by theenlarged head 771 bears against the distal end 766 of the stem portion760 of the support pedestal 750. A distal wall 773 defined by theenlarged head 771 provides a seating surface for an axially steppedportion 821 of a proximal wall 820 of a cylindrical base 816 of thedrive fitting 814. The sleeve bushing 770 defines a central,longitudinal passageway 775 that defines a portion of the throughbore716 of the motor end coupling 714.

In one exemplary embodiment, the proximal, thin walled casing portion762 of the support pedestal 750 is crimped onto the outer casing 704 ofthe casing assembly 702 to secure the support pedestal 750 to the casing704 and thereby couple or secure the coupling body 720 to the casing704. Those of skill in the art would recognize that there are a numberof alternative approaches to securing the motor end coupling 714 to thecasing 704 including molding and adhesive means. A proximally extendingportion of the thin walled casing portion 762 extending rearward fromthe coupling body 720 functions as a stress relief sleeve so as to avoidundesirable kinking of the flexible shaft drive transmission 700 at theinterface of the outer casing 704 and the coupling body 720.

As will be explained below, the drive motor coupling 915 includes alatching mechanism 960 that releasably secures the motor end coupling714 to the drive motor coupling 915 thereby achieving an engaged stateof the two couplings 714, 915. The latching mechanism 960 includes apush button latch 960 a that moves or slides orthogonally or radiallywith respect to the drive motor axis of rotation RMD and thelongitudinal axis LASDT of the shaft drive transmission 700. As can bestbe seen in FIGS. 17, 21 and 28, the proximal end wall 744 of thecoupling body 720 of the motor end coupling 714 is engaged by an upperor top portion 967 of a latching region 965 of the push button latch 960a of the latching mechanism 960 to secure the motor end coupling 714 tothe drive motor coupling 915. The latching mechanism 960 of the drivemotor coupling 915 provides a quick connect-quick disconnect feature forthe coupling and uncoupling of the motor end coupling 714 and the drivemotor coupling 915. That is, the latching interconnection between themotor end coupling 714 and the drive motor coupling 915, together withthe ribs/channel engagement structure of the coupling body 720 of themotor end coupling 714 and the tapered collar 950 of the drive motorcoupling 915 allow the operator of the power operated knife 100 toengage or couple shaft drive transmission 700 to the drive motorassembly 900 using only one hand by simply pushing the coupling body 720of the motor end coupling 714 up into the tapered collar 950 of thedrive motor coupling 915 with one hand thereby allowing the latchingregion 965 of the push button latch 960 a to latch against the steppedshoulder 744 and thereby operatively engaging the motor end coupling 714to the drive motor coupling 915. Conversely, the operator need onlydepress an actuator 961 of the push button latch 960 a with a finger torelease the latching region 965 of the push button latch 960 a from theproximal end wall 744 of the coupling body 720 and thereby release atdisengage the motor end coupling 714 from the drive motor coupling 915.

The flexible shaft drive transmission 700 further comprises theelongated drive shaft assembly 800 rotatable within the outer casingassembly 702. As is best seen in FIGS. 22-24, the drive shaft assembly800 includes the flex shaft 802 comprising a flexible metal core 804. Inone exemplary embodiment, the metal core 804 is surrounded by one ormore helical windings about the core 804. The drive shaft assembly 800further includes the driven fitting 814 at the drive motor end 810 ofthe drive shaft assembly 800 and the drive fitting 884 at the poweroperated rotary knife end 880 of the drive shaft assembly. The drivenfitting 814 includes a cylindrical base 816 and a shaft 850 extendingproximally from a proximal wall 820 of the cylindrical base 816. Theshaft 850 defines a central socket 852. The central socket 852 extendsdistally from a proximal end 854 of the shaft 850 and receives a distalend portion 806 (FIG. 21) of the flex shaft 802. The driven fittingshaft 850 may be secured to the end portion 806 of the flex shaft 802 invaries ways including crimping and adhesive attachment.

As can best be seen in FIG. 21, the proximal wall 820 of the cylindricalbase 816 includes an axially stepped central portion 821. The steppedcentral portion 821 of the proximal wall 820 functions as a seatingsurface for the driven fitting 814. Specifically, the stepped centralportion 821 rotates on and bears against the distal wall 773 of theenlarged head 771 of the sleeve bushing 770 of the motor end coupling714

The cylindrical base 816 of the driven fitting 814 includes a planarupper surface 818. Extending axially from the planar upper surface 818is a locating member 822. In one exemplary embodiment, the locatingmember 822 comprises a central tapered projection 824 projecting axiallyin the distal direction DISTRAN from the planar upper surface 818 of thecylindrical base 816. The locating member 822 is radially surrounded bya plurality of vanes 830 projecting axially in the distal directionDISTRAN from the planar upper surface 818 of the cylindrical base 816and radially outwardly from the tapered projection 824. In one exemplaryembodiment, the plurality of vanes 830 comprises six vanes. A portion828 of the locating member 822 extends distally beyond the six vanes 830and terminates in a distal end 826 of the locating member 822. Each ofthe six vanes 830 includes a drive engagement face 832, a back wall 834and a radial outer surface 836. The radial outer surface 836 of each ofthe vanes 830 is congruent and coextensive with a radial outer surface840 of the cylindrical base 816.

As can best be seen in FIG. 22, for each vane 830, the engagement face832 is substantially vertical, that is, a plane through the engagementface 832 would be substantially parallel to a portion of the centrallongitudinal axis LASDT of the flexible shaft drive transmission 700extending through the driven fitting 814 and the planes through each ofthe engagement faces 832 would intersect in a line substantiallycoextensive with the portion of the central longitudinal axis LASDT ofthe shaft drive transmission 700 extending through the driven fitting814. Also, as can best be seen in FIG. 22, for each vane 830, anincluded angle IA is defined by the engagement face 832 and the backwall 834. In one exemplary embodiment, the included angle would beapproximately 25°, the diameter of the driven fitting 814 would beapproximately 0.75 inches, a total height of the driven fitting 814 fromthe proximal wall 820 to the distal end 826 of the locating member 822would be approximately 0.56 inches.

When the motor end coupling 714 is in an engaged state with the drivemotor coupling 915, the drive fitting 972 of the drive motor assembly900 is in operative or driving engagement with driven fitting 814 of thedrive shaft assembly 800. When the drive motor 901 is actuated, thedrive fitting 972 drives or rotates the driven fitting 814 which, inturn, rotates the flex shaft 802 and the male drive fitting 884 of thedrive shaft assembly 800. As can best be seen in FIG. 25, the six vanes830 of the driven fitting 814 of the drive shaft assembly 800 interfitinto respective cavities 991 formed between the radially spaced apartsix vanes 982 of the drive fitting 972 of the drive motor assembly 900.Similarly, the six vanes 982 of the drive fitting 972 interfit intorespective cavities 842 formed between the radially spaced apart sixvanes 830 of the driven fitting 814. The interfitting of the vanes 830of the driven fitting 814 and the vanes of the drive fitting 972, asschematically illustrated in FIG. 25, defines the drive engagementstructure 1002 of the drive connection structure 1000 of the presentdisclosure.

When the motor end coupling 714 is in an engaged state with the drivemotor coupling 915, the drive fitting 972 of the drive motor assembly900 is in operative or driving engagement with driven fitting 814 of thedrive shaft assembly 800, as shown in FIG. 25, the forward portion 828of the tapered central projection 824 of the locating member 822 of thedriven fitting 814 extends axially into the tapered central opening 984of the locating member 992 of the drive fitting 972. The interfitting ofthe tapered central projection 824 of the driven fitting 814 into thetapered central opening 984 of the drive fitting 972 defines the axiallocating structure 1004 of the present disclosure. In one exemplaryembodiment, the locating member 992 of the drive fitting 972 comprisesthe tapered central opening 984 defined in a cylindrical body 976 of thedrive fitting 972 of the drive motor assembly 900. The interfitting ofthe locating member forward portion 828 of the driven fitting 814 andthe central opening 984 of the drive fitting 972 helps to insure propercoaxial alignment between the motor drive axis of rotation RMS and theflex shaft axis of rotation RFS.

Also, when the motor end coupling 714 is an engaged state with the drivemotor coupling 915 and the drive motor 901 actuated, the driveengagement faces 832 of the six projecting vanes 830 are operativelyengaged and rotated by corresponding drive engagement faces 984 of sixprojecting vanes 982 of the cylindrical body 976 of the drive fitting972. The use of six interfitting vanes 830, 982 of the driven fitting814 and the drive fitting 972 insures, at most, a small rotation(rotation required would be 60° or less) of the motor end coupling 814with respect to the drive motor coupling 915, allowing for one-handedquick connection of the motor end coupling 814 and the drive motorcoupling 915.

The interfitting of the six vanes 830 of the driven fitting 814 with thesix vanes 982 of the drive fitting 972 results in a drive connectionbetween the drive motor assembly 900 and the flexible shaft drivetransmission 700 that comprises six planar surfaces, namely, thecontacting drive engagement faces 832, 984 of the driven fitting 814 ofthe drive shaft assembly 800 and the drive fitting 972 of the drivemotor assembly 900. The use of six planar drive engagement facesadvantageously results in a large total drive contact area.Additionally, the use of six planar contact surfaces mitigates a problemassociated with prior motor drive-shaft drive transmission driveconnections which utilized a square drive fitting at the end of thedrive transmitting shaft and a mating square socket fitting affixed tothe drive shaft of the drive motor. Specifically, in such prior driveconnections, the vertices of the square male fitting of the drivetransmitting shaft tended to become rounded off over time therebybecoming loose or sloppy in the square socket fitting resulting in aninitial “clunking” in the drive connection when the drive motor wasactuated by the operator to drive the power operated rotary knife. Theuse of six planar drive engagement faces in the drive connection of thepresent disclosure overcomes the problem of rounded off vertices of asquare mail fitting and the associated “clunking” problem upon actuationof the power operated rotary knife 100.

The outer casing assembly 702 of the flexible shaft drive transmission700 also includes the handle assembly coupling 784 at the second orpower operated knife end portion 701 b of the shaft drive transmission700. The handle assembly coupling 784 includes a distal portion 786 thatextends into the throughbore 258 of the elongated central core 252 ofthe hand piece retaining assembly 250 of the power operated rotary knifehandle assembly 110. The handle assembly coupling 784 of the outercasing assembly 702 includes a coil spring 792 (FIGS. 1 and 7) thatbiases both the male drive fitting 884 of the drive shaft assembly 800to a disengaged position or state with respect to female fitting 622 ofthe pinion gear and the handle assembly coupling 784 to a disengagedposition or state with respect to the handle assembly 110 of the poweroperated rotary knife 100. That is, when the latch 276 of the driveshaft latching assembly 275 is depressed by the operator of the poweroperated rotary knife 100, the coil spring 792 functions to operativelydisengage the drive connection between the flexible shaft drivetransmission 700 and the power operated rotary knife 100. A stressrelief sleeve 790 is molded onto the second end 780 of the outer casing704 and transitions between the outer casing 704 and the handle assemblycoupling 784 so as to avoid undesirable kinking of the shaft drivetransmission 700 at the interface of the outer casing 704 and the handleassembly coupling 784.

Drive Motor Assembly 900

The drive motor assembly 900, in one exemplary embodiment, includes thedrive motor 901, a drive motor cover 902 (shown in FIGS. 8-11) and themotor coupling 915. As best seen in FIG. 11, the drive motor cover 902defines a cavity 902 a which receives the drive motor 901 and the drivemotor coupling 915 extends through an opening 902 b in a lower or distalend of the cover 902. The drive motor cover 902 also includes aremovable access panel 903 a which may be removed for purposes ofobtaining access to the drive motor 901. A pivoting mounting bracket 903b that pivots with respect to the cover 902 is provided allowing forhorizontal, vertical or angled mounting of the mounting bracket 903 b,while the drive motor 901 remains oriented in a vertical position withinthe cover 902. Affixed to an outer surface of the access panel 903 a isa rotary knife hanger 903 c. The rotary knife hanger 903 c allows theoperator to hang the power operated rotary knife 100 out of harm's waywhen the knife 100 is not in use. The power operated rotary knife 100 ishung by its distal end by positioning the knife 100 such that the hangerextends through the cutting opening CO defined by the rotary knife blade300 and the blade housing 400.

In one exemplary embodiment, the drive motor 901 comprises a brushlessDC servo motor. By way of example and without limitation, oneappropriate drive motor is an Elwood Gettys Model M423-SAYO-OUOY-3K DCservo motor manufactured by Elwood Corporation, 2701 North Green BayRoad, Racine, Wis. 53404 (www.elwood.com). The drive motor 901 includesa drive motor body 904 and is supplied power and control signals via apair electrical cables 910 which extend through a pair of sealedconnectors 912 which are affixed to the drive motor body 904 and allowthe cables 910 pass into the interior of the drive motor body 904.

The drive motor 901 includes a motor drive shaft 970 that extends from adistal end of the drive motor body 904. As used herein, with respect tothe drive motor assembly 901, the terms distal or distal directionDISMOT shall mean in a direction from the drive motor body 904 towardthe flexible shaft drive transmission 700. The terms proximal orproximal direction PRXMOT shall mean the opposite direction. That is, ascan be seen in FIG. 17, a bottom cap 940 of the motor coupling 915 isdistal or in a distal direction DISMOT with respect to drive motor body904, while the drive shaft 970 is proximal or in a proximal directionPRXMOT with respect to the bottom cap 940 of the motor coupling 915.Affixed to the motor drive shaft 970 is a cooling fan 913 having aplurality of radially extending fins 914 that rotate with the driveshaft 970 for air circulation/cooling purposes.

Also affixed to a distal end of the motor drive shaft 970 is the drivefitting 972. The structure and function of drive fitting 972 has beendescribed previously. The drive fitting 972 includes the enlargedcylindrical body 980 extending distally (in the direction DISMOT FIG.25) from the cylindrical shaft 976. As can best be seen in FIGS. 14, 25and 26, the cylindrical shaft 976 defines a keyed opening 978 whichreceives the drive motor shaft 970. The drive fitting 972 is secured tothe drive motor shaft 970 by a pair of set screws 974. The cylindricalbody 980 of the drive fitting 972 includes the distal planar surface981. The plurality of vanes 982, radially spaced apart by the pluralityof cavities 991, extend distally from the distal planar surface 981.Each of the plurality of vanes 982 includes the drive or engagement face984, the back wall 986 and the radial outer surface 988, whichcorresponds to the radial outer surface 990 of the cylindrical body 980.The dimensions of the plurality of vanes 982 of the drive fitting 972are approximately the same as the dimensions of the plurality of vanes830 of the driven fitting 814 as the two fittings 814, 972 areconfigured to interfit, as shown schematically in FIG. 25. The planardistal surface 981 of the cylindrical body 980 of the drive fitting 972also includes the locating member 992, which interfits with the locatingmember 822 of the driven fitting 814. In one exemplary embodiment, thelocating member 992 of the drive fitting 972 comprises the taperedcentral opening 994 in the planar surface 981 which receives the taperedcentral projection 824 of the driven fitting 814 for axial alignmentpurposes, as explained previously.

As can best be seen in FIGS. 14-17, the drive motor coupling 915includes a coupling housing 916 including a coupling upper housing 920,a coupling lower housing 930 and the bottom cap 940. In one exemplaryembodiment, the upper housing 920, the lower housing 930 and the bottomcap 940 are separately fabricated of a durable plastic material and aresecured together via a pair of shoulder screws 946. However, one ofskill in the art would recognize that there are numerous ways tofabricate the coupling housing 916, other than utilizing three separatecomponents.

The coupling upper housing 920 includes a cylindrical body 921 and aflange 922 extending from a proximal end of the cylindrical body 921.The flange 922 includes four bosses 923, one at each corner, extendingin a proximal direction from the flange 922. Each of the four bosses 923includes an axially extending threaded opening 924. The drive motor body904 includes a drive motor body mounting flange 906 at a distal end ofthe drive motor body 904. The drive motor body mounting flange 906includes four apertures 908 that are configured to axially align withthe threaded openings 924 such that four screws 947 secure the couplinghousing 916 to the drive motor body 904.

As is best seen in FIGS. 14A and 17, the coupling lower housing 930includes an outer surface 931 and a distal or lower end 933 of the lowerhousing 930. The lower housing outer surface 931 includes a recess thatreceives the actuator 961 of the push button latch 960 a of the latchingmechanism 960. The lower housing distal end 933 includes a recess 934which provides clearance for a sliding body portion 962 of the pushbutton latch 960 a of the latching mechanism 960. The coupling lowerhousing 930 includes an inner surface 935 that defines a generally crossshaped central opening 936. A planar side wall 937 defining part of thelower housing inner surface 935 is configured to provide clearance for aspring arm 948 b of a flat spring 948. As will be explained below, theflat spring 948 is supported by the bottom cap 940 and functions to biasthe push button latch 960 a to an engagement position.

As can best be seen in FIGS. 14A and 16, the coupling bottom cap 940includes proximal or upper wall 944, a lower or distal wall 945, and aninner surface 942. The inner surface 942 defines a central opening 943.The bottom cap 940 includes a pair of threaded openings 941 that receivethe two shoulder screws 946. The proximal wall 944 of the bottom cap 940includes a planar recesses region 944 a that provides clearance for anend 948 c of the flat spring. As best seen in FIG. 17, the proximal wallrecessed region 944 a includes an axially extending opening 944 b thatreceives and supports a stem 948 a of the flat spring 948.

As can best be seen in FIGS. 14A, 16-18 and 26-28, the motor endcoupling 915 include the tapered collar 950 and a wave spring 949, whichfunctions to bias the tapered collar to a down or distal position (inthe direction DISMOT with respect to the drive motor coupling 915). Themotor end coupling 915 also includes the latching mechanism 960 and aflat spring 948, which biases the push button latch 960 a to anengagement position, that is, a position wherein the push button latch960 a is contacting the proximal end wall 744 of the coupling body 720to releasably secure the motor end coupling 714 to the drive motorcoupling 915.

The tapered collar 950 includes a central cylindrical body 951 andradially extending wings 952. Each of the wings 952 defines a verticallyextending aperture 953 (FIG. 14A) and the central cylindrical body 951includes an inner surface 954 that defines a tapered, generallyfrustoconical central opening 955. As can be seen in FIG. 26, thecentral opening 955 includes a proximal end 955 a and a distal end 955b, the distal end 955 b being larger in diameter than the proximal end955 a. The inner surface 954 of the tapered collar 950 includes theplurality of tapered raised ribs 956 and the plurality of taperedchannels 957, as previously described, which engage and interfit,respectively, with the tapered channels 740 and tapered raised ribs 734of the coupling body 720 of the motor end coupling 714. In one exemplaryembodiment, as can be seen in FIG. 26, each of the ribs 956 (and alsothe channels 957) are tapered, that is, a distal end 956 b of each ofthe tapered ribs 956 is wider in circumferential distance or are than aproximal end 956 a of the rib 956. Additionally, in one exemplaryembodiment, each of the raised ribs 956 is of substantially uniformheight above the respective adjacent channels 957 from the distal end956 b to the proximal end 956 a of the rib 956. Further, in oneexemplary embodiment, the taper angle of the frustoconical taperedcollar or cone 732 of the coupling body 720 of the motor end coupling714 is substantially equal to a taper angle (approximately 10° withrespect to the drive motor shaft center line CLMDS) of the frustoconicalcentral opening 955 of the tapered collar 950 of the motor coupling 915to ensure a snug fit between the coupling body 720 and the taperedcollar 950.

The tapered collar 950 is slidingly supported on the two shoulder screws946 (FIG. 18) that extend through the axially extending apertures 953 ofthe wings 952 of the tapered collar 950. The shoulder screws 946 passthrough openings 928 in a distal or lower wall 926 of the coupling upperhousing 920 and thread into the threaded openings 941 of the couplingbottom cap 940 to secure the bottom cap 940, the coupling lower housing930, and the tapered collar 950 to the upper housing 940. The taperedcollar 950 is biased to the down or distal position by the wave spring949. The wave spring 949 is seated between a stepped shoulder 925 formedin the proximal wall 926 of the coupling upper housing 920 and a steppedshoulder 959 of a proximal wall 958 of the tapered collar 950.

The latching mechanism 960 includes the push button latch 960 a and theflat spring 948, which functions to bias the push button latch 960 a toan engagement position (shown in FIGS. 26 and 28) and away from adeflected position (shown in FIG. 27). As can best be seen in FIGS. 14A,16-17 and 26-28, the push button latch 960 a includes the actuator 961which, in its engagement position, is generally flush with the outersurface of the coupling lower housing 930. The actuator 961 may bepushed radially inwardly by the operator of the power operated knife 100to move the push button latch 960 a to its deflected position andthereby allow the disengagement of the motor end coupling 714 from thedrive motor coupling 915. This may be accomplished by the operator usinga single hand. The recess 932 defined in the outer surface 931 of thecoupling lower housing 930 allows for radial inward movement of the pushbutton latch 960 a.

The push button latch 960 a further includes the planar sliding bodyportion 962. The sliding body portion 962 slides in the recess 934defined in the distal end 933 of the lower housing 930 and includes acentral opening 964. As can best be seen in FIG. 16, in the engagementposition, the central opening 964 of the latch 960 a of the latchingmechanism 960 is slightly offset from the central opening 943 defined bythe coupling bottom cap 940. In this way, as the operator pushes themotor end coupling 714 upwardly into the central opening 943 of thebottom cap, the outer surface 721 of the coupling body 720 will contactan inner portion 968 (FIGS. 16 and 26) of a latching region 965 of thesliding body portion 962 of the latch 960 a and push the sliding bodyportion 962 radially such that the latch 960 a of the latching mechanism960 is forced to its deflected position. As can best be seen in FIGS. 17and 28, when the motor end coupling 714 is engaged with the drive motorcoupling 915 and the latch 960 a of the latching mechanism 960 is in theengagement position, a top portion 967 of the latching region 965engages the proximal end wall 744 of the coupling body 720 of the motorend coupling 714 to secure the couplings 714, 915 in the engaged state.

The push button latch 960 a of the latching mechanism 960 is biased tothe engagement position by the flat spring 948. Specifically, anengagement region 948 d of the flat spring 948 contacts and bearsagainst a projection 966 of the latch 960 a of the latching mechanism960. The flat spring 948 has a generally U-shaped configuration andincludes the stem portion 948 a and the spring arm 948 a. The flatspring 948 is secured in place with respect to the coupling housing 916by the stem 948 a which is received in the axial opening 944 b of thecoupling bottom cap 940 to secure the spring 948. The spring arm 948 bof the flat spring 948 includes the end portion 948 c which defines theengagement region 948 d. As explained previously, the engagement region948 d contacts and bears against the projection 966 of the push buttonlatch 960 a to bias the latch 960 a of the latch mechanism 960 to theengagement position.

As best seen in FIGS. 26-28, the wave spring 949 biases the taperedcollar 950 to the down position (FIGS. 26 and 28). However, when theoperator of the power operated knife 100 seeks to engage the motor endcoupling 714 of the flexible shaft drive transmission 700 with the motordrive coupling 915 of the motor drive assembly 900, he or she pushesupwardly (in the direction labeled UP′ or DISTRAN in FIG. 26) with thecoupling body 720 of the motor end coupling 714 against the taperedcollar 950 of the drive motor coupling 915. Urging the coupling body 720upwardly against the tapered collar 950 compresses the wave spring 949and moves the tapered collar 950 upwardly with respect to the couplinghousing 916. As the tapered collar 950 slides upwardly along theshoulder screws 946 and the coupling body 720 moves upwardly, the outersurface 721 of the coupling body 720 contacts the latching region 965 ofthe push button latch 960 a of the latching mechanism 960 and slides thelatch 960 a radially from an engagement position (schematically shown inFIGS. 26 and 28) to a deflected position (schematically shown in FIG.27). When the coupling body 720 has moved in the upward direction asufficient distance (a distance schematically shown and labeled asCOLLAR TRAVEL in FIG. 27), the proximal end wall 744 of the couplingbody 720 clears the top portion 967 of the latching region 965 of thepush button latch 960 a allowing the latch 960 a to snap back to itsengagement position. As mentioned previously, the push button latch 960a of the latching mechanism 960 is biased to its engagement position(shown in FIGS. 26 and 28) by the flat spring 948. In the engagementposition, the top portion 967 of the latching region 965 of the pushbutton latch 960 a abuts the proximal end wall 744 of the coupling body720 to secure the motor end coupling 714 to the drive motor coupling915.

Engagement of Shaft Drive Transmission-Drive Motor Assembly

FIGS. 25-28 schematically illustrate the drive connection structure1000, the drive engagement structure 1002 and the axial locatingstructure 1004 of the flexible shaft drive transmission 700 and thedrive motor assembly 900 of the present disclosure and furtherschematically illustrate a method or process to proceed from anon-engaged state (where the motor end coupling 714 and the drive motorcoupling 915 are not in the engaged state) to the engaged stated wherethe motor end coupling 714 of the shaft drive transmission 700 and thedrive motor coupling 915 of the drive motor assembly 900 are coupledtogether such that the driven fitting 814 of the drive shaft assembly800 is operatively engaged by the drive fitting 972 of the drive motorassembly 900. FIGS. 26 and 27 schematically shows the motor end coupling714 of the shaft drive transmission 700 and the drive motor coupling 915of the drive motor assembly 900 in a non-engaged state, while FIG. 28schematically shows the motor end coupling 714 and the drive motorcoupling 915 in the engaged state.

As shown in FIG. 26, assuming that the drive motor assembly 900 is in afixed position, the operator of the power operated rotary knife 100grasps and manipulates the motor end portion 701 a of the shaft drivetransmission 700 (grasping the outer casing 705 just below or proximalto the motor end coupling 710) with respect to the drive motor assembly900 so as to axially align the tapered coupling body 720 of the motorend coupling 714 and the tapered collar 950 of the drive motor coupling915 such that the driven fitting 814 of the drive shaft assembly 800 isaligned for entry into the central opening 943 of the bottom cap 940 ofthe motor end coupling 915 (and thereby aligned for entry into thecentral, frustoconical opening 955 defined by the interior surface 954of the central cylindrical body 951 of the tapered collar 950).

As is seen in FIG. 27, after alignment, the motor end coupling 714 ismoved in an upward direction UP′ (or distal direction DISTRAN) withrespect to the drive motor assembly 900. As explained previously, theouter surface 721 of the coupling body 720 contacts the inner portion968 of the latching region 965 of the sliding body portion 962 of thepush button latch 960 a of the latching mechanism 960 and forces thelatch 960 a to move in a radial direction, orthogonal to the drive motoraxis of rotation RMD to its deflected position. A distance that thelatch 960 a moves radially before the engaged state is achieved is shownschematically as a distance labeled LATCH TRAVEL in FIG. 27. Also, asthe motor end coupling 714 continues to be moved in the upward directionUP, the coupling body 720 contacts the tapered collar 950 forcing thecollar 950 to slide upwardly along the shoulder screws 946 therebydepressing the wave spring 949. A distance that the tapered collar 950moves upwardly before the proximal end wall 744 of the coupling body 720clears the top portion 967 the latching region 965 of the push buttonlatch 960 a thereby allowing the latch 960 a to returned to itsengagement position by the flat spring 948 is shown schematically as adistance labeled COLLAR TRAVEL in FIG. 27. Depending upon the specificalignment of the ribs 734 and channels 740 of the coupling body 720 andthe ribs 956 and channels 957 of the tapered collar 950 of the motor endcoupling 915, as the motor end coupling 714 contacts the drive motorcoupling 915 and causes the tapered collar 950 to slide upwardly, aslight rotation (60° or less) of the motor end coupling 714 may berequired to facilitate proper alignment of the respective ribs andchannels and accomplish full engagement of the coupling body 720 and thetapered collar 950.

The engagement position of the push button latch 960 a is shown indashed line in FIG. 27, while the deflected position of the latch 960 ais shown in solid line. Comparing a relative compression of the flatspring 948 between FIGS. 27 and 26 & 28, also illustrates the radialmovement of the push button latch 960 a when moving between theengagement and deflected positions. When the upward movement of thetapered collar 950 is sufficient such that the inner portion 968 of thelatching region 965 of the sliding body portion 962 clears the proximalend wall 744 of the coupling body 720, the sliding body portion 962 isbiased or returned to its engagement position by the flat spring 948, asshown in FIG. 28.

The engaged state of the motor end coupling 714 and the drive motorcoupling 915 is shown schematically in FIG. 28. As shown in FIG. 28, thetop portion 967 of the latching region 965 of the sliding body portion962 bears against the coupling body 720 and thereby secures the motorend coupling 714 to the drive motor coupling 915. In the engaged stateof the couplings 714, 915, the driven fitting 814 of the drive shaftassembly 800 operatively engages the drive fitting 972 of the drivemotor assembly 900.

When the motor end coupling 714 of the flexible shaft drive transmission700 is in the engaged state with the drive motor coupling 915 of thedrive motor assembly 900 and the drive motor 901 is actuated, the driveshaft assembly 800 is rotated by the drive fitting 972 of the drivemotor assembly 900. The drive shaft assembly 800, in turn, is coupled toand rotates a gear train 604 of the power operated rotary knife 100. Thegear train 604 of the power operated rotary knife 100 engages the set ofgear teeth 328 of the driven gear 328 of the rotary knife blade 300 torotate the knife blade 300 about the central axis of rotation R.

Advantageously, the wave washer or wave spring 949 facilitatesengagement or coupling between the coupling body 720 of the motor endcoupling 714 and tapered collar 950 of the drive motor coupling 915. Thewave spring 949 permits the tapered collar 950 of the drive motorcoupling 915 to move in the upward direction UP′ (FIG. 26) a sufficientextent to provide clearance between the latching region 965 of thesliding body portion 962 of the push button latch 960 a and the proximalend wall 744 of the coupling body 720 of the motor end coupling 714 suchthat the push button latch 960 a can snap into its engagement positionto couple the coupling body 720 of the motor end coupling 714 and thetapered collar 950 of the drive motor coupling 915. Further, after theengagement position of the push button latch 960 a has been achieved andthe coupling body 720 of the motor end coupling 714 is coupled to thetapered collar 950 of the drive motor coupling 915, the wave spring 949continues to apply downward pressure (in the direction DW′ in FIG. 26)to the tapered collar 950 and, thereby, forces the tapered collar 950against the coupling body 720. Recall that the coupling body 720 isprecluded from axial movement in the downward direction DW′ by theengaged push button latch 960 a. The snug fit between the tapered collar950 and the coupling body 720 mitigates vibration when the drive motor901 is actuated. Additionally, the snug fit facilitated by the wavespring 949 ensures a full and complete engagement between the drivenfitting 814 of the drive shaft assembly 800 and the drive fitting 972 ofthe drive motor assembly 900. It is important to consistently maintain aconstant distance between the top portion or surface 967 of the pushbutton latch 960 a and the planar surface 981 of the cylindrical body980 of the drive fitting 972 for full and complete engagement betweenthe driven fitting 814 and the drive fitting 972.

Should the operator of the power operated rotary knife 100 wish toremove the flexible shaft drive transmission 700 from the motor driveassembly 900, that is, go to the non-engaged state of the motor endcoupling 714 and the drive motor coupling 915, he or she need only todepress the actuator 961 of the push button latch 960 a of the latchingmechanism 960. Assuming that the drive motor 901 is oriented generallyvertically with the drive motor coupling 915 facing the ground, themotor end coupling 714 will simply fall away from the motor end coupling915 toward the ground. Thus, both going from the non-engaged state tothe engaged state and going from an engaged state to a non-engaged staterequires the operator to use only a single hand. Thus, the driveconnection structure 1000 of the present disclosure is properly termed aquick connect and quick disconnect connection structure.

Second Exemplary Embodiment—Flexible Shaft Drive Transmission

A second exemplary embodiment of a flexible shaft drive transmissionassembly of the present disclosure is shown generally 1700 in FIGS.29-31. The flexible shaft drive transmission assembly 1700, like theflexible shaft drive transmission 700 previously described, isconfigured to transmit rotational power from the drive motor 901 to apower operated tool, such as the power operated rotary knife 100. Theflexible shaft drive transmission assembly 1700 includes a flexibledrive shaft transmission 1701 and a driver assembly 2000. The flexibledrive shaft transmission 1701 includes a first or motor end portion 1701a, a second or tool end portion 1701 b and an elongated, flexiblecentral portion 1701 c extending between the motor end portion 1701 aand the tool end portion 1701 b. A length of the flexible drive shafttransmission 1701 will depend upon the application, but may range inlength from three to six feet or more. The driver assembly 2000 isreleasably coupled to the tool end portion 1701 b of the shaft drivetransmission 1701, for example, by threaded engagement. The driverassembly 2000, which includes a main tube 2000 and a driver shaftassembly 2020 a rotatably supported within the main tube 2000, isconfigured to releasably engage the handle assembly 110 of the poweroperated knife 100. When in an engaged state, the driver assembly 2000is operatively coupled between the tool end portion 1701 b of the shaftdrive transmission 1701 and the handle assembly 110 of the poweroperated rotary knife 10X) and the shaft drive transmission 1701 isoperatively coupled to the drive motor coupling 915. The shaft drivetransmission assembly 1700, including the shaft drive transmission 1701and the driver assembly 2000, transmit rotational power from the drivemotor 901 to the gear train 604 of the power operated rotary knife 100.

The shaft drive transmission 1701 includes an outer casing assembly 1702and a drive shaft assembly 1800 rotatably supported within the outercasing assembly 1702. The outer casing assembly 1702 includes a drivemotor end, a tool end, and a flexible central or middle portion 1702 c,shown generally at 1702 a, 1702 b, 1702 c, respectively. The outercasing assembly 1702 comprises a flexible, tubular outer casing 1704(corresponding generally to the central portion 1702 c) having an innersurface 1705 defining a throughbore 1706, a first or motor end coupling1714 (corresponding generally to the drive motor end 1702 a) affixed toa first or motor end 1710 of the outer casing 1704, and a second ordriver assembly coupling 1782 (corresponding generally to the tool end1702 b) affixed to a distal or tool end 1780 of the outer casing 1704.The drive shaft assembly 1800 includes a flexible, elongated drivetransmitting shaft or flex shaft 1802 and a driven fitting 1814 coupledto a first or motor end 1810 of the flex shaft 1802 and a couplerfitting 1880 coupled to a second or tool end 1860 of the flex shaft1802.

The configuration of the motor end portion 1701 a of the shaft drivetransmission 1701, including the motor end coupling 1714 and the drivenfitting 1814, are substantially identical in structure and function tothe motor end portion 701 a of the shaft drive transmission 700,previously described. Accordingly, the motor end portion 1701 a of theshaft drive transmission 700 will not be discussed in detail, rather,reference is made to the prior description which is incorporated herein.With respect to the tool end portion 1701 b of the shaft drivetransmission 1701, as described hereinafter, the directions of distaland proximal, labeled as DISTOOL and PRXTOOL in FIGS. 29, 30 and 34,shall refer to the following: the distal direction DISTOOL shall begenerally in a direction along the shaft drive transmission assembly1700 away from the motor end portion 1701 a of the shaft drivetransmission 1701 and toward the power operated rotary knife 100 and theproximal direction PRXTOOL shall be generally in a direction along theshaft drive transmission assembly 1700 away from the power operatedrotary knife 100 and toward the motor end portion 1701 a of the shaftdrive transmission 1701.

The shaft drive transmission assembly 1700 is part of a power operatedtool assembly, like the power operated tool assembly 10, and provides adrive interface or drive connection structure, shown generally at 3000in FIG. 30, for operatively coupling the flexible shaft drivetransmission 1700 and the gear train of a power operated tool, such asthe gear train 604 of the power operated rotary knife 100, fortransmitting motive or rotational power from the drive motor 901 of thedrive motor assembly 900 to the gear train 604 of the power operatedrotary knife 100. The shaft drive transmission-power operated toolconnection structure 3000 includes a rotational drive structure totransmit rotational power from the flex shaft 1802 of the flexible shaftdrive transmission 1701 to the gear train 604 of the power operatedrotary knife 100 and a physical connection or coupling structure tocouple the flexible shaft drive transmission 1701 to the handle assembly110 of the power operated rotary knife 100.

The rotational drive structure includes: a driver shaft assembly 2020 aof the driver assembly 2000 including a driver shaft 2020, a drivenfitting 2032 and a driver fitting 2060; and the drive shaft assembly1800 of the shaft drive transmission 1701 including the coupler fitting1880 and a flex shaft fitting 1864 coupled to the distal end 1810 of theflex shaft 1802, all of which are operatively connected to transmitrotational power from the flex shaft 1802 to the gear train 604 of thepower operated rotary knife 100. The physical connection structureincludes: the driver assembly coupling 1782 of the outer casing assembly1702 of the shaft drive transmission 1701; a casing coupler 2070 and themain tube 2001 of the driver assembly 2000; and the drive shaft latchingassembly 275 of the handle assembly 110 of the power operated rotaryknife 100, all of which combine to provide the physical connection orcoupling between the shaft drive transmission 1701 and the poweroperated rotary knife 100. When the driver assembly 2000 is operativelycoupled between the driver assembly coupling 1782 of the shaft drivetransmission 1700 and the handle assembly 110 of the power operatedrotary knife 100 (engaged state), rotation of the flex shaft 1802 causesrotation of the gear train 604 of the power operated knife 100 which, inturn, causes rotation of the rotary knife blade 300 of the poweroperated rotary knife.

More specifically, the coupler fitting 1880 is coupled to a distal endof the flex shaft 1802. The coupler fitting 1880 is configured to have adrive fitting 1892 at its distal end. The drive fitting 1892 of thecoupler fitting 1880 engages a driven fitting 2032 formed at a proximalend of the driver shaft 2020 of the driver assembly 2000. The driverfitting 2060 is coupled to a distal end of the driver shaft 2020. Thedriver fitting 2060 engages the input shaft 612 of the pinion gear 610,the pinion gear 610 being part of the gear train 604 of the poweroperated rotary knife 100, as previously described. Thus, rotation ofthe flex shaft 1802 causes rotation of the coupler fitting 1880, thedriver shaft 2020, the pinion gear 610, the drive gear 650 and,ultimately, the rotary knife blade 300.

The driver assembly 2000 includes the main tube 2001, the casing coupler2070 and a latch collar 2100. The main tube 2001 and casing coupler 2070are configured to enter into the elongated central core 252 of the handpiece retaining assembly 250 of the power operated rotary knife 100 andbe engaged by the drive shaft latching assembly 275. When the driveshaft latching assembly 275 engages the driver assembly 2000 (as shownin FIG. 30), the shaft drive transmission assembly 1700 is operativelyengaged or is in the engaged state with respect to the power operatedrotary knife 100, that is, the driver shaft 2020 of the driver assembly2000 operatively engages the pinion gear 610 of the power operatedrotary knife gear train 604 such that rotation of the drive motor 901rotates the rotary knife blade 300 of the power operated rotary knife100.

To enhance the expected operating life of the shaft drive transmission1701, during fabrication of the shaft drive transmission 1701, alubricant 2300 (shown schematically at 2300 in FIG. 33), such aslubricant grease, is injected into a gap or void V between a metal core1804 comprising the drive transmitting shaft or flex shaft 1802 of thedrive shaft assembly 1800 and the inner surface 1705 of the outer casing1704 of the outer casing assembly 1702. Advantageously, the flexibledrive shaft transmission 1701 of the present disclosure is designed andconfigured to be a sealed lubrication component. That is, after aninitial injection or application of lubricant 2300 in the void V duringfabrication of the shaft drive transmission 1701, there is no necessityto remove the flex shaft 1802 from the outer casing 1704 in order toinject or apply additional lubricant during the course of the expectedoperating life of the flexible shaft drive transmission 1701. This is amarked improvement and advantage over prior shaft drive transmissionswherein disassembly of the transmission and lubrication was required atperiodic intervals of approximately every 20 operating hours. In oneexemplary embodiment, as the expected operating life of the flexibleshaft drive transmission 1701 is on the order of 1000 hours or more,approximately 50 or more disassembly and lubrication procedures would beavoided utilizing the shaft drive transmission 1701 of the presentdisclosure. Elimination of periodic lubrication provides a significantlabor and cost savings over the expected operating life of the shaftdrive transmission 1701, as well as reducing downtime inherent indisassembly and lubrication procedures.

The shaft drive transmission 1701 of the present disclosure isspecifically configured to effectively be a sealed, non-serviceableunit. That is, an enlarged head section 1888 of the coupler fitting1880, which defines a distal end of the drive shaft assembly 1800, isconfigured to have a larger diameter than a diameter of a throughbore1796 of a sleeve bushing 1795 of the driver assembly coupling 1782 ofthe outer casing assembly. The enlarged head section 1888 of the couplerfitting 1888 thus effectively limits axial movement of the flex shaft1802 with respect to the outer casing 1704 in the proximal directionPRXTOOL and thereby prevent removal of the flex shaft 1802 from themotor end 1710 of the outer casing 1704 (i.e., moving the flex shaft1802 in the proximal direction PRXTOOL with respect to the outer casing1704). Similarly, the driven fitting 1814 at the proximal end of theflex shaft 1802 is configured to have a diameter that is larger than acorresponding diameter of a central opening of the coupling body 1720 ofthe motor end coupling 1714 of the outer casing assembly 1702. Thedriven fitting 1814 of the drive shaft assembly 1860 thus effectivelylimits axial movement of the flex shaft 1802 with respect to the outercasing 1704 in the distal direction DISTOOL and thereby prevent removalof the flex shaft 1802 from the tool end 1780 of the outer casing 1704(i.e., moving the flex shaft 1802 in the distal direction DISTOOL withrespect to the outer casing 1704).

A cylindrical reduced diameter proximal section 1894 of the couplerfitting 1880 is rotatably, but snugly received within a cylindricalthroughbore 1796 defined by the sleeve bushing 1795. That is, there isvery close fit or engagement between the cylindrical reduced diameterproximal section 1894 of the coupler fitting 1880 and the cylindricalthroughbore 1796 of the sleeve bushing 1795. Advantageously, the closefit between the cylindrical proximal section 1894 of the coupler fitting1880 and an inner surface 1795 b defining the cylindrical throughbore1796 of the sleeve bushing 1795 effectively provides a seal between therotating drive shaft assembly 1800 and the driver assembly coupling 1782of the outer casing assembly 1702 to inhibit and mitigate leakage of thelubricant 2300 from the tool end portion 1701 b of the shaft drivetransmission 1701. When the power operated tool assembly 10 is inoperation, typically, the drive motor 901 is mounted on a hangerpositioned above the work area where the power operated rotary knife 100is manipulated by an operator to trim or cut a product. Thus, the motorend portion 1701 a of the flexible shaft drive transmission 1701 istypically at a higher vertical position than the tool end portion 1701 bof the shaft drive transmission 1701. Because of the lower verticalposition of the tool end portion 1701 b of the shaft drive transmission1701, gravity tends to cause the lubricant 2300 to migrate or draintoward the driver assembly coupling 1782. Thus, inhibiting leakage ofthe lubricant 2300 between the drive transmitting shaft 1802 and thedriver assembly coupling 1782 of the outer casing assembly 1702 is ofprime importance. Additionally, the close fit between the driven fitting1814 of the drive shaft assembly 1800 and the motor end coupling 1714 ofthe outer casing assembly 1702 also mitigates leakage of lubricant 2300from the motor end portion 1701 a of the shaft drive transmission 1701.

Driver Assembly Coupling 1782 of Outer Casing Assembly 1702

As can best be seen in FIGS. 32 and 33, the driver assembly coupling1782 of the outer casing assembly 1702 is affixed to the second end 1780of the outer casing 1704. The driver assembly coupling 1782 includes anouter surface 1783 and an inner surface 1784. The inner surface 1784defines a throughbore 1785 extending between and passing through adistal end wall 1793 and a proximal end wall 1794. The driver assemblycoupling 1782 includes a central cylindrical body 1786 and stress reliefproximal sleeve 1787 that overlies a distal portion 1781 of the outercasing 1704 to mitigate kinking of the second end 1780 of the outercasing 1704 as the operator manipulates the power operated rotary knife100 during cutting or trimming operations.

In one exemplary embodiment, the driver assembly 2000 is releasablycoupled to the driver assembly coupling 1782 by threaded engagement.Accordingly, as can best be seen in FIG. 32, the driver assemblycoupling 1782 includes a reduced diameter distal section 1788, having ata threaded portion 1789 adjacent the distal end wall 1793. The threadedportion 1789 of the driver assembly coupling 1782 is threadedly engagedby a threaded proximal end 2092 of an enlarged proximal portion 2082 ofan inner surface 2076 of the casing coupler 2070 to secure the driverassembly 2000 to the outer casing assembly 1702.

As can best be seen in FIG. 33, the diver assembly coupling 1782 locatesand supports the sleeve bushing 1795. In one exemplary embodiment, acylindrical body 1797 of the sleeve bushing 1795 is press fit into thethroughbore 1785 of the driver assembly coupling 1782. Specifically, asection 1791 of the inner surface 1784 defining the throughbore 1785defines a seating surface for the cylindrical body 1797 of the sleevebushing 1795. A radially outwardly stepped shoulder 1792 defined betweenthe central cylindrical body 1786 and the reduced diameter distalsection 1788 receives and seats the enlarged distal head 2098 of thesleeve bushing 1795. When the drive assembly 2000 is coupled to thedriver assembly coupling 1782, a thrust bearing washer 2150 (FIG. 32) isdisposed adjacent a shoulder 1788 a formed in the outer surface 1783 ofthe driver assembly coupling 1782 and is sandwiched between a distal endwall 2110 of the latch collar 2100 and a proximal end wall 2094 of thecasing coupler 2070 of the driver assembly 2000.

Coupler Fitting 1880 and Flex Shaft Fitting 1864

The drive shaft assembly 1800 includes the previously discussed couplerfitting 1880. In one exemplary embodiment, the coupler fitting 1880comprises a coupler screw 1881 that is coupled to the flex shaft 1802via a threaded connection. It should be understood, that otherconnection structures between the flex shaft 1802 and the couplerfitting 1880 may be utilized, such as, without limitation, welding,brazing, soldering, use of one or more fasteners, press fit, crimping,adhesive attachment, etc., as would be understood by one of skill in theart. As is best seen in FIGS. 32 and 33, in one exemplary embodiment, aflex shaft fitting 1864 is interposed between a distal end section 1862of the flex shaft 1802 and the coupler screw 1881 and functions tosecure the coupler screw 1881 to the flex shaft 1802. Specifically, theflex shaft fitting 1864 includes an enlarged diameter proximal section1868 and a reduced diameter distal section 1870. A cylindrical sleeve1872 is defined by the proximal section 1868 of the flex shaft fitting1864. The sleeve 1872 receives the distal end section 1862 of the flexshaft 1802 and, in one exemplary embodiment, the sleeve is crimped ontothe flex shaft end section 1862 to affix the flex shaft fitting 1864 tothe flex shaft 1802. An outer surface 1866 of the flex shaft fitting1864 in the region of the reduced diameter distal section 1870 definesexternal threads 1874.

The external threads 1874 of the flex shaft fitting 1864 are sized toreceive corresponding mating internal threads 1896 of the coupler screw1880 to affix the coupler screw 1880 to the flex shaft fitting 1864 andthereby secure the coupler screw 1880 to the flex shaft 1880.Preferably, the mating threads 1874, 1896 of the flex shaft fitting 1864and the coupler screw 1880 are left handed threads. The drive motor 901rotates the flex shaft 1802 and the driver shaft 2020 in acounter-clockwise direction (labeled CCW in FIG. 35) as viewed from themotor end portion 1701 a of the shaft drive transmission 1701.Advantageously, the left handed threaded engagement of the coupler screw1881 and the flex shaft fitting 1864 insures that as the flex shaft 1802rotates, any relative rotational movement between the flex shaft fitting1864 and the coupler screw 1881 will tighten, rather than loosen, theengagement of the flex shaft fitting 1864 and the coupler screw 1881.The engagement between the flex shaft fitting 1864 and the coupler screw1881 is limited by a radially outwardly extending shoulder 1876 in theouter surface 1866 of the flex shaft fitting 1864.

As can best be seen in FIGS. 37-39, the coupler screw 1881 comprises anenlarged distal section 1888 and the reduced diameter proximal section1894 and includes an outer surface 1882 and an inner surface 1884. Theinner surface 1884 defines a throughbore 1886 extending between andthrough a distal end wall 1897 and a proximal end wall 1898. As notedpreviously, when the driver assembly 2000 is coupled to the driverassembly coupling 1782 of the outer casing assembly 1702, the distal endwall 1897 of the coupler screw 1881 abuts the stepped shoulder 2084 ofthe inner surface 2076 of the casing coupler 2070 of the driver assembly2000. The proximal end wall 1898 of the coupler screw 1881 abuts thestepped shoulder 1896 of the flex shaft fitting 1864.

In one exemplary embodiment, the inner surface 1884 of the coupler screw1881 forming the throughbore 1886 in the region of the enlarged distalsection 1888 defines a female off-round distal section 1890. Theoff-round distal section 1890 defines a female drive fitting 1892. Thefemale drive fitting 1892 is configured to receive the mating drivenfitting 2032 of the driver shaft 2020 of the driver assembly 2000. Byway of example and without limitation, the cross sectional shape of theoff-round distal section 1890 defining the fitting 1892 may be a square(as shown in FIGS. 38 and 39), a triangle, a pentagon or a more complexpolygon shape such as splined or vaned configuration or a star-shaped(i.e., Torx™) configuration. Additionally, the drive fitting 1892 couldbe a male fitting and the corresponding driven fitting 2032 could be afemale fitting, as would be understood by one of skill in the art,without impacting the functionality of the drive connection between thecoupler screw 1881 and the driver shaft 2020.

In one exemplary embodiment, the flex shaft 1802 may be fabricated ofmultiple spiral wrapped windings of steel or steel alloy wire or othermaterial or materials known to have comparable properties. The outercasing 1704 which comprises a flexible tube may be fabricated of one ormore layers of a durable plastic or other material or materials know tohave comparable properties or rubber composition or a plastic or rubbercomposition reinforced by one or more braided or spiral windings ofsteel or steel alloy wire between the layers. The driver assemblycoupling 1782 and flex shaft fitting 1864 may be fabricated of steel,stainless steel, or steel alloy or other material or materials know tohave comparable properties. The coupler screw 1880 may be fabricated ofa hardenable grade of alloy steel or a hardenable grade of stainlesssteel, or other material or materials known to have comparableproperties and may be formed/shaped by machining, forming, casting,forging, extrusion, metal injection molding, and/or electrical dischargemachining or another suitable process or combination of processes.

Driver Assembly 2000

When a flexible shaft drive transmission 1701 has reached the end of itsuseful operational life, because the shaft drive transmission 1701 isnon-serviceable, it is expected to be discarded. However, the driverassembly 2000 is expected to have an operational life substantiallylonger than the flexible drive transmission 1701. Thus, the driverassembly 2000 is designed and configured to be removed from an exhaustedflexible shaft drive transmission 1701 and reattached to a new shaftdrive transmission 1701. As can best be seen in FIGS. 34-36 and 40-45,the driver assembly 2000 comprises the driver shaft 2020 and the driverfitting 2060 which function as the rotational drive connection betweenthe flex shaft 1802 of the shaft drive transmission 1701 and the geartrain 604 of the power operated rotary knife 100 and the main tube 2001,the casing coupler 2070 and a biasing spring 2200 which function toprovide a releasable physical coupling between the tool end portion 1701b and the handle assembly 110 of the power operated rotary knife 100.The main tube 2001 (FIG. 40) comprises an enlarged diameter centralsection 2005, a reduced diameter distal section 2006 and a reduceddiameter proximal section 2007 and includes an outer surface 2002 and aninner surface 2003. The inner surface 2003 of the main tube 2001 definesa throughbore 2004 that extends between and through a distal end wall2014 and a proximal end wall 2016 of the tube 2001.

As can best be seen in FIG. 30, when the driver assembly 2000 is coupledto the handle assembly 110 of the power operated rotary knife 100, themain tube 2001 extends into the elongated central core 252 of the handpiece retaining assembly 250. The outer surface 2002 of the main tube2001 includes a radially outwardly extending shoulder 2008 that bridgesthe enlarged diameter central section 2005 and the reduced diameterdistal section 2006. The outer surface 2002 of the main tube 2001 alsoincludes a tapered outwardly extending shoulder 2009 that bridges theenlarged diameter central section 2005 and the reduced diameter proximalsection 2007. The shoulder 2009 functions to constrain a proximal endsection 2204 of the biasing spring 2200 from moving axially in thedistal direction DISTOOL A distal end wall 2098 of the casing coupler2070 functions to constrain the proximal end section 2204 of the biasingspring 2200 from moving axially in the proximal direction PRXTOOL.

Driver Shaft 2020

As is best seen in FIGS. 34 and 35, the driver shaft assembly 2020 aincludes the driver shaft 2020 and the driver fitting 2060. The drivershaft assembly 2020 a is supported for rotation within the main tube bya first, distal sleeve bushing 2040 and a second, proximal sleevebushing 2050. The first and second sleeve bushings 2040, 2050 eachinclude an outer surface 2041, 2051, respectively, and an inner surface2042, 2052, respectively. The respective inner surfaces 2042, 2052 ofthe distal and proximal sleeve bushings 2040, 2050 define axiallyaligned cylindrical throughbores 2043, 2053, that is, when the driverassembly 2000 is coupled to the handle assembly 110 of the poweroperated rotary knife 100, the throughbores 2043, 2053 are axiallyaligned with respect to the longitudinal axis LA of the power operatedrotary knife 100 and are also axially aligned with a centrallongitudinal axis LASDT (FIG. 29) of the shaft drive transmission 1701,a centerline CLFS′ through the flex shaft 1802 and a central axis ofrotation RFS′ of the flex shaft 1802. The inner surfaces 2042, 2052 ofthe distal and proximal sleeve bushings 2040, 2050 define a pair ofaxially spaced apart, cylindrical bearing support surfaces 2042 a, 2052a that rotatably support the driver shaft 2020.

Advantageously, the distal and proximal sleeve bushings 2040 are affixedto respective opposite walls 2014, 2016 of the main tube 2001. In thisway, an axial spacing between the respective cylindrical bearing supportsurfaces 2042 a, 2052 a provided by the sleeve bushings 2040, 2050 forthe rotating driver shaft 2020 are a maximum length possible, given theaxial length of the main tube 2001. That is, given the axial length ofthe main tube 2001 along the central longitudinal axis LASDT′,positioning the distal and proximal sleeve bushings 2040, 2050 atopposite ends 2014, 2016 of the main tube 2001 insures that as great anaxial distance as possible separates the cylindrical bearing supportsurfaces 2042 a, 2052 a. Axially spacing the cylindrical bearing supportsurfaces 2042 a, 2052 a within the main tube 2001 advantageouslymaintains the driver shaft 2020 straight and concentric with the centrallongitudinal axis LASDT′ of the shaft drive transmission 1701 and thecentral axis of rotation RFS′ of the flex shaft 1802, as possible givenmanufacturing variations.

The distal and proximal sleeve bushings 2040, 2050 each include acylindrical body 2044, 2054 and an enlarged head 2046, 2056. In oneexemplary embodiment, the respective cylindrical bodies 2044, 2054 arepress fit into the throughbore 2004. The cylindrical body 2044 of thedistal sleeve bushing 2040 is press fit into the reduced diameter distalsection 2006 of the main tube 2001 such that the enlarged head 2046abuts the distal end wall 2014, while the cylindrical body 2054 of theproximal sleeve bushing 2050 is press fit into the reduced diameterproximal section 2007 of the main tube 2001 such that the enlarged head2056 abuts the proximal end wall 2016.

The driver shaft 2020 (FIG. 35) includes a central region or portion2022 surrounded by a reduced diameter distal portion 2024 and anenlarged diameter proximal portion 2026. The reduced diameter distalportion 2024 includes a threaded section 2028, while the enlargeddiameter proximal portion 2026 includes an off-round proximal endsection 2030. The off-round proximal end section 2030 defines a drivenfitting 2032, that in one exemplary embodiment, is square in crosssection to matingly engage the square cross section drive fitting 1892of the coupler screw 1880. The driver shaft 2020 includes a proximal endwall 2038 at one end and a distal end wall 2037 at the opposite end. Thethreaded section 2028 of the driver shaft 2020, adjacent the distal endwan 2037, is received in a mating internal threaded opening 2064 of thedriver fitting 2060. The threaded connection between the threadedsection 2028 of the driver shaft 2020 and the threaded opening 2064 ofthe driver fitting 2060 is preferably is a left handed threadedconnection for the reasons let forth previously with respect to thethreaded connection between the external threads 1874 of the flex shaftfitting 1864 and the internal threaded section 1896 of the coupler screw1880.

The driver shaft 2020 includes a pair of axially spaced apart slightlyenlarged diameter regions 2034, 2036 disposed at opposite ends of thecentral region 2022. The enlarged diameter regions 2034, 2036 are seatedrespectively in the cylindrical bearing support surfaces 2042 a, 2052 aof the distal and proximal sleeve bushings 2040, 2050. A distal end wall2047 defined by the enlarged head 2046 of the distal sleeve bushing 2040functions as a bearing surface for the rotating driver fitting 2060.Specifically, as can be seen in FIG. 36, a proximal end wall 2068defined by an enlarged head 2067 of the distal sleeve bushing 2040 abutsthe distal end wall 2047 of the driver fitting 2060 to limit orconstrain movement of the driver shaft 2020 with respect to the maintube 2001 in the rearward or proximal direction PRXTOOL. Similarly, adistal end wall 2058 defined by the enlarged head 2056 of the proximalsleeve bushing 2050 functions as a bearing surface for the rotatingdriver fitting 2060. Specifically, the enlarged diameter proximalportion 2026 of the driver shaft 2020 includes a cylindrical stop 2039.The cylindrical stop 2039 (FIG. 36) of the proximal portion 2026 of thedriver shaft 2020 abuts a proximal end wall 2058 of the enlarged head2056 of the proximal sleeve bushing 2050 to limit or constrain movementof the driver shaft 2020 with respect to the main tube 2001 in theforward or distal direction DISTOOL.

Driver Fitting 2060

The driver fitting 2060 comprises a distal drive body 2064 and anenlarged proximal head 2067 and includes an outer surface 2062. Thedrive body 2067 defines a drive fitting 2069 that is sized andconfigured to be received in the input shaft 612 of the pinion gear 610of the gear train 602 of the power operated rotary knife 100 and, whenrotated, to rotate the pinion gear 610. When the driver assembly 2000 isin the engaged state with respect to the handle assembly 110 of thepower operated rotary knife 100, the drive fitting 2069 engages thefemale socket of fitting 622 defined by the pinion gear input shaft 612such that rotation of the driver shaft 2020 rotates the pinion gear 610and the drive gear 650 of the gear train 602 thereby causing rotation ofthe rotary knife blade 300 of the power operated rotary knife 100. Thedrive body 2064 includes a cylindrical base 2065 and four angled vanes2066 extending outwardly from the cylindrical base 2065. Theconfiguration of the drive body 2064 is determined by the configurationof the female socket 622 of the pinion gear 610.

As previously mentioned, the internal left handed threaded opening 2064which passes through the driver fitting 2060 receives the threadeddistal end 2028 of the driver shaft 2020. Additionally, the proximal endwall 2068 of the enlarged proximal head 2067 of the driver fitting 2000abuts the distal end wall 2047 of the enlarged head 2046 of the distalsleeve bushing 2040 to limit movement of the driver shaft 2020 withrespect to the main tube 2001 in the rearward or proximal directionPRXTOOL.

Casing Coupler 2070

The casing coupler 2070, best seen in FIGS. 43-45, comprises acylindrical body 2072 including an outer surface 2074 and the innersurface 2076. A throughbore 2078 is defined by the inner surface 2076and includes a reduced diameter distal portion 2080 of the throughbore2078 and the enlarged diameter proximal section 2082 of the throughbore2078. The outer surface 2074 of the casing coupler 2070 includes areduced diameter distal section 2084 and a reduced diameter proximalsection 2085 on either side of an enlarged diameter central section2088. The function of the casing coupler 2070 is to releasably connectthe driver assembly coupling 1782 of the outer casing assembly 1702 tothe main tube 2001. As such, in one exemplary embodiment, the casingcoupling 2070 includes two threaded regions to accomplish the connectionstructure via a pair of threaded engagements. First, the reduceddiameter distal portion 2080 of the throughbore 2078 includes aninternal threaded distal end 2091. The threaded distal end 2091 isconfigured to thread onto the threaded distal end 1789 of the driverassembly coupling 1782. Second, the enlarged diameter proximal portion2082 of the throughbore 2078 includes an internal threaded proximal end2092. The threaded proximal end 2092 is configured to thread onto thethreaded outer surface 2018 of the proximal section 2007 of the maintube 2001. When both threaded engagements are accomplished, the driverassembly 2000 is secured to the driver assembly coupling 1782 of theshaft drive transmission 1701 and the driver assembly driver shaft 2020and driver fitting 2060 are operatively coupled to the pinion gear 610of the power operated rotary knife 100 and the flex shaft 1802 of theshaft drive transmission 1701.

The enlarged diameter central section 2088 of the outer surface 2074 ofthe casing coupler includes a generally cone-shaped outwardly extendingsection 2095. The cone-shaped section 2095 includes an outer cylindricalrim 2096. The reduced diameter distal section 2084 of the outer surface2074 of the cylindrical body 2072 of the casing coupler 2070 includes anopposing pair of flats 2097. The pair of flats 2097 facilitate threadingand unthreading of the casing coupler 2070 using an end wrench (notshown).

Latch Collar 2100

As can best be seen in FIG. 33, the latch collar 2100 includes an outersurface 2102 and an inner surface 2104. The inner surface 2104 defines acylindrical throughbore 2106 sized to slide onto the reduced diameterdistal section 1788 of the driver assembly coupling 1782. A centralsection 2108 of the latch collar 2110 includes an outwardly extendingcone-shaped surface 2110. A stepped shoulder 2112 is formed between theoutwardly extending cone-shaped surface 2110 and a reduced diameterproximal section 2114 of the spacer ring 2100. The cone-shaped surface2110 includes an outer cylindrical rim 2116. As can be best be seen inFIG. 30, the stepped shoulder 2112 functions as a radial securementgroove. The stepped shoulder 2112 is engaged by the latch 276 of thedrive shaft latching assembly 275 of the power operated rotary knife 100to secure the driver assembly 2000 and the flexible shaft drivetransmission 1701 with respect to the handle assembly 110, as is shownin FIG. 30, that is, the flexible shaft drive transmission assembly 1700is in the engaged state with respect to the handle assembly 110 of thepower operated rotary knife 100.

Biasing Spring 2200

The coiled spring 2200 comprises a coiled body 2202 including aplurality of spiraled coils and a proximal end section 2204 with reduceddiameter coils. The proximal end section 2204 of the coiled spring 2200is disposed around the reduced diameter proximal section 2007 of themain tube 2001. The coiled spring 2200 is constrained from axialmovement in the distal direction DISTOOL with respect to the main tube2011 by the tapered outwardly extending shoulder 2008 of the main tube2011 and is constrained from axial movement in the proximal directionPRXTOOL with respect to the main tube 2011 by the distal end wall 2098of the cylindrical body 2072 of the casing coupler 2070.

When the driver assembly 2000 is in the engaged state with respect tothe handle assembly 110 of the power operated rotary knife 100, a distalsection 2206 (FIG. 36) of the coiled body 2202 of the biasing spring2200 bears against an inwardly stepped shoulder 267 (FIG. 30) of theinner surface 254 of the elongated central core 252 of the hand pieceretaining assembly 250 and functions to bias the driver assembly 2000 inthe proximal direction PRXTOOL with respect to the handle assembly 110of the power operated rotary knife 100. The biasing spring 2200 performsat least two functions when the driver assembly is in the engaged state:a) The biasing spring 2200 moves the driver assembly 2000 away from thehandle assembly 110 to a disengaged state whenever the latch 276 of thedrive shaft latching assembly 275 is depressed to move the latch 276away from engagement with the stepped shoulder 2112 of the latch collar2100, b) When the driver assembly 2000 is in the engaged or coupledstate with respect to the handle assembly 110, the biasing spring 2200is in a compressed state (FIG. 30). As such, the biasing spring 2200biases or forces the main tube 2001, the casing coupler 2070 and theouter casing assembly 1702 in the proximal direction PRXTOOL. Thisbiasing force necessarily taking up the small amount of axial slackexisting between the tool drive members (driver shaft 2020, couplerscrew 1880 and flex shaft 1802) and the physical coupling members (maintube 2001, casing coupler 2070, driver assembly coupling 1782 and outercasing 1704). Taking up the slack between the tool drive members and thephysical coupling members forces the tool drive members to move relativeto the physical coupling members in the distal direction DISTOOL. Thisadvantageously results in the driver fitting 2060 moving in the distaldirection DISTOOL to a full engagement position within the input shaft612 of the pinion gear 610.

The axial slack between the drive members and the physical couplingmembers of the flexible shaft drive transmission assembly 1700necessarily exists because of manufacturing tolerances, that is, in ashaft drive transmission 1701 that may be eight feet in axial length, itis essentially impossible because of manufacturing tolerances to matchthe total axial length of the tool drive members and the total axiallength of the physical coupling members. Thus, some slack is built intothe axial lengths such that the drive members have some limited axialmovement or slack with respect to the corresponding physical couplingmembers. The proximal directed force of the biasing spring 2200advantageously and effectively functions to take up this slack andinsure a complete and full engagement of the driver fitting 2060 withinthe pinion gear input shaft 610.

When the driver assembly 2000 is not engaged to the handle assembly 110of the power operated rotary knife 100, the latch collar has limitedaxial sliding movement on the distal section 1788 of the driver assemblycoupling 1782 between the washer 2150 and the outwardly stepped shoulder1792 of the driver assembly coupling 1782. However, when the driverassembly 2000 is in the engaged state, the latch collar 2100 isprevented from moving axially in the proximal direction PRXTOOL by thelatch 276 of the drive shaft latching assembly 275 of the power operatedrotary knife 100 to secure the driver assembly 2000 and the flexibleshaft drive transmission 1701 with respect to the handle assembly 110.As described above, when the driver assembly 2000 is in the engagedstate, the biasing spring functions to force the main tube 2001, thecasing coupler 2070 and the outer casing assembly 1702 in the proximaldirection PRXTOOL. This causes the latch collar 2100 to slide on thedistal section 1788 of the drive assembly coupling 1782 in the distaldirection DISTOOL and bear against the thrust bearing washer 2150.Specifically, a front wall 2115 (FIG. 33) of the latch collar 2100 bearsagainst the thrust bearing washer 2150 when the driver assembly 2000 isin the engaged state.

The driver assembly 2000 is constrained or held in place radially withinthe elongated central core 252 of the handle assembly 100 by: a) a snugfit between a portion 2002 a of the outer surface 2002 in the centralsection 2005 of the main tube 2001 and a necked down section 254 a ofthe inner surface 254 of the elongated central core 252; b) a close fitbetween the outer rim 2096 of the cone-shaped outwardly extendingsection 2095 of the casing coupler 2070 and an enlarged proximal portion254 b of the inner surface 254 of the elongated central core 252; and c)a close fit between the outer rim 2116 of the cone-shaped outwardlyextending surface 2110 of the latch collar 2100 and the enlargedproximal portion 254 b of the inner surface 254 of the elongated centralcore 252.

The driver assembly 2000 is constrained or held in place axially bybearing between the latch collar 2100 against the latch 276 of the driveshaft latching assembly 275 and, more specifically, the bearing of theshoulder 2112 of the latch collar 2100 against the latch 276 to restrainmovement of the driver assembly 2000 in the proximal direction PRXTOOLand the biasing of the coiled spring 2200 against the distal end wall2098 of the casing coupler 2070 to restrain movement of the driverassembly in the distal direction DISTOOL. In FIG. 30, the biasing spring2200 is shown in a compressed condition, abutting the inwardly steppedshoulder 267 of the elongated central core 252.

In one exemplary embodiment, the driver shaft 2020 may be fabricated ofa sold piece of steel or stainless steel or other material or materialsknown to have comparable properties. The main tube 2001, the casingcoupler 2070, biasing spring 2200 and the latch collar 2100 arepreferably fabricated of steel, a steel alloy or stainless steel orother material or materials known to have comparable properties. Thedistal and proximal sleeve bushings 2040, 2050 are preferably fabricatedof bronze or brass or other material or materials known to havecomparable properties. The driver fitting 2060 is preferably fabricatedof steel, a steel alloy or stainless steel or other material ormaterials known to have comparable properties.

As used herein, terms of orientation and/or direction such as front,rear, forward, rearward, distal, proximal, distally, proximally, upper,lower, inward, outward, inwardly, outwardly, horizontal, horizontally,vertical, vertically, axial, radial, longitudinal, axially, radially,longitudinally, etc., are provided for convenience purposes and relategenerally to the orientation shown in the Figures and/or discussed inthe Detailed Description. Such orientation/direction terms are notintended to limit the scope of the present disclosure, this application,and/or the invention or inventions described therein, and/or any of theclaims appended hereto. Further, as used herein, the terms comprise,comprises, and comprising are taken to specify the presence of statedfeatures, elements, integers, steps or components, but do not precludethe presence or addition of one or more other features, elements,integers, steps or components.

What have been described above are examples of the presentdisclosure/invention. It is, of course, not possible to describe everyconceivable combination of components, assemblies, or methodologies forpurposes of describing the present disclosure/invention, but one ofordinary skill in the art will recognize that many further combinationsand permutations of the present disclosure/invention are possible.Accordingly, the present disclosure/invention is intended to embrace allsuch alterations, modifications, and variations that fall within thespirit and scope of the appended claims.

What is claimed is:
 1. A flexible shaft drive transmission coupled between a drive motor and a gear train of a power operated tool, the flexible shaft drive transmission comprising: a) an outer casing assembly having a drive motor end and a tool end and including a driver assembly coupling including a central cylindrical body and a reduced diameter distal section and an inner surface defining a throughbore extending through a proximal end wall and a distal end wall of the driver assembly coupling, the inner surface including a stepped shoulder spaced from the proximal and distal end walls, a bushing including an enlarged distal head and a cylindrical body extending from the enlarged distal head received in the throughbore of the driver assembly coupling, the enlarged distal head of the bushing seated against the stepped shoulder of the inner surface of the driver assembly coupling, the bushing defining a longitudinal central opening; and b) an elongated drive transmitting shaft assembly rotatable within the outer casing assembly, the elongated drive transmitting shaft assembly including a flexible drive transmitting shaft having a motor end and a tool end, the drive transmitting shaft assembly further including a coupler fitting coupled to the tool end of the drive transmitting shaft, the coupler fitting including a body and an enlarged head extending distally from the body, the body fitting within the longitudinal central opening of the bushing and the enlarged head having a diameter greater than a diameter of the longitudinal central opening of the bushing to constrain axial movement of the drive transmitting shaft with respect to the outer casing.
 2. The flexible shaft drive transmission of claim 1 wherein the body of the coupler fitting is cylindrical and the longitudinal central opening of the bushing is longitudinal.
 3. The flexible shaft drive transmission of claim 2 wherein the longitudinal central opening of the bushing is concentric with a central longitudinal axis of the flexible shaft drive transmission.
 4. The flexible shaft drive transmission of claim 1 wherein the enlarged head of the coupler fitting defines a drive fitting aligned with a central axis of rotation of the drive transmitting shaft assembly.
 5. The flexible shaft drive transmission of claim 4 wherein the drive fitting comprises a square drive fitting.
 6. The flexible shaft drive transmission of claim 1 wherein a shaft fitting is affixed to the tool end of the drive transmitting shaft and the coupler fitting is secured to the shaft fitting to couple the coupler fitting to the tool end of the drive transmitting shaft.
 7. The flexible shaft drive transmission of claim 6 wherein the coupler fitting is secured to the shaft fitting via a threaded interconnection.
 8. The flexible shaft drive transmission of claim 1 wherein the outer casing assembly includes an outer casing extending between a first coupling at the drive motor end of the outer casing assembly and a second coupling at the tool end of the outer casing assembly.
 9. The flexible shaft drive transmission of claim 8 wherein the bushing is disposed in the second coupling.
 10. The flexible shaft drive transmission of claim 1 further including a driver assembly coupled to the tool end of the outer casing assembly and comprising a driver shaft coupled to the enlarged head of the coupler fitting of the drive transmitting shaft assembly.
 11. A flexible shaft drive transmission assembly coupled between a drive motor and a gear train of a power operated tool, the flexible shaft drive transmission assembly comprising: a) a flexible drive shaft transmission including: 1) an outer casing assembly having a drive motor end and a tool end and including a driver assembly coupling including a central cylindrical body and a reduced diameter distal section and an inner surface defining a throughbore extending through a proximal end wall and a distal end wall of the driver assembly coupling, the inner surface including a stepped shoulder spaced from the proximal and distal end walls, a bushing including an enlarged distal head and a cylindrical body extending from the enlarged distal head received in the throughbore of the driver assembly coupling, the enlarged distal head of the bushing seated against the stepped shoulder of the inner surface of the driver assembly coupling a bushing including an enlarged distal head and a cylindrical body extending from the enlarged distal head received in the throughbore of the driver assembly coupling, the enlarged distal head of the bushing seated against the stepped shoulder of the inner surface of the driver assembly coupling, the bushing defining a longitudinal central opening; and 2) an elongated drive transmitting shaft assembly rotatable within the outer casing assembly, the elongated drive transmitting shaft assembly including a flexible drive transmitting shaft having a motor end and a tool end, the drive transmitting shaft assembly further including a coupler fitting coupled to the tool end of the drive transmitting shaft, the coupler fitting including a body and an enlarged head extending distally from the body, the body fitting within the longitudinal central opening of the bushing and the enlarged head having a diameter greater than a diameter of the longitudinal central opening of the bushing to constrain axial movement of the drive transmitting shaft with respect to the outer casing; and b) a driver assembly including a tube assembly releasably coupled to the tool end of the outer casing assembly and an elongated driver shaft assembly at least partially disposed within the tube assembly and operatively coupled to coupler fitting of the drive transmitting shaft assembly.
 12. A flexible shaft drive transmission coupled between a drive motor and a gear train of a power operated tool, the flexible shaft drive transmission comprising: a) an outer casing assembly having a drive motor end and a tool end and including an outer casing and a driver assembly coupling affixed to a tool end of the outer casing assembly, the driver assembly coupling including a distal end wall and a proximal end wall and a thoughbore extending longitudinally therebetween, the driver assembly coupling including a central cylindrical body and a reduced diameter distal section extending from the central cylindrical body and having a threaded portion on an outer surface of the reduced diameter distal portion adjacent the distal end wall of the driver assembly coupling and a bushing positioned within the throughbore of the driver assembly coupling at the tool end of the outer casing assembly, the bushing defining a longitudinal central opening; and b) an elongated drive transmitting shaft assembly rotatable within the outer casing assembly, the elongated drive transmitting shaft assembly including a flexible drive transmitting shaft having a motor end and a tool end, the drive transmitting shaft assembly further including a coupler fitting coupled to the tool end of the drive transmitting shaft, the coupler fitting including a body and an enlarged head extending distally from the body, the body fitting within the longitudinal central opening of the bushing and the enlarged head having a diameter greater than a diameter of the longitudinal central opening of the bushing to constrain axial movement of the drive transmitting shaft with respect to the outer casing.
 13. The flexible shaft drive transmission of claim 12 wherein the body of the coupler fitting is cylindrical and the longitudinal central opening of the bushing is longitudinal.
 14. The flexible shaft drive transmission of claim 13 wherein the longitudinal central opening of the bushing is concentric with a central longitudinal axis of the flexible shaft drive transmission.
 15. The flexible shaft drive transmission of claim 12 wherein the enlarged head of the coupler fitting defines a drive fitting aligned with a central axis of rotation of the drive transmitting shaft assembly.
 16. The flexible shaft drive transmission of claim 15 wherein the drive fitting comprises a square drive fitting.
 17. The flexible shaft drive transmission of claim 12 wherein a shaft fitting is affixed to the tool end of the drive transmitting shaft and the coupler fitting is secured to the shaft fitting to couple the coupler fitting to the tool end of the drive transmitting shaft.
 18. The flexible shaft drive transmission of claim 17 wherein the coupler fitting is secured to the shaft fitting via a threaded interconnection.
 19. The flexible shaft drive transmission of claim 12 wherein the outer casing assembly includes the outer casing extending between a first coupling at the drive motor end of the outer casing assembly and the driver assembly coupling at the tool end of the outer casing assembly.
 20. The flexible shaft drive transmission of claim 12 wherein an inner surface of the driver assembly coupling defines the throughbore and includes a stepped shoulder spaced from the proximal and distal end walls, the enlarged distal head of the bushing being seated against the stepped shoulder.
 21. The flexible shaft drive transmission of claim 12 further including a driver assembly coupled to the tool end of the outer casing assembly and comprising a driver shaft coupled to the enlarged head of the coupler fitting of the drive transmitting shaft assembly. 